diff --git a/vendor/google.golang.org/grpc/dialoptions.go b/vendor/google.golang.org/grpc/dialoptions.go
new file mode 100644
index 0000000..9f872df
--- /dev/null
+++ b/vendor/google.golang.org/grpc/dialoptions.go
@@ -0,0 +1,589 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"time"
+
+	"google.golang.org/grpc/backoff"
+	"google.golang.org/grpc/balancer"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/grpclog"
+	"google.golang.org/grpc/internal"
+	internalbackoff "google.golang.org/grpc/internal/backoff"
+	"google.golang.org/grpc/internal/envconfig"
+	"google.golang.org/grpc/internal/transport"
+	"google.golang.org/grpc/keepalive"
+	"google.golang.org/grpc/resolver"
+	"google.golang.org/grpc/stats"
+)
+
+// dialOptions configure a Dial call. dialOptions are set by the DialOption
+// values passed to Dial.
+type dialOptions struct {
+	unaryInt  UnaryClientInterceptor
+	streamInt StreamClientInterceptor
+
+	chainUnaryInts  []UnaryClientInterceptor
+	chainStreamInts []StreamClientInterceptor
+
+	cp          Compressor
+	dc          Decompressor
+	bs          internalbackoff.Strategy
+	block       bool
+	insecure    bool
+	timeout     time.Duration
+	scChan      <-chan ServiceConfig
+	authority   string
+	copts       transport.ConnectOptions
+	callOptions []CallOption
+	// This is used by v1 balancer dial option WithBalancer to support v1
+	// balancer, and also by WithBalancerName dial option.
+	balancerBuilder balancer.Builder
+	// This is to support grpclb.
+	resolverBuilder             resolver.Builder
+	channelzParentID            int64
+	disableServiceConfig        bool
+	disableRetry                bool
+	disableHealthCheck          bool
+	healthCheckFunc             internal.HealthChecker
+	minConnectTimeout           func() time.Duration
+	defaultServiceConfig        *ServiceConfig // defaultServiceConfig is parsed from defaultServiceConfigRawJSON.
+	defaultServiceConfigRawJSON *string
+	// This is used by ccResolverWrapper to backoff between successive calls to
+	// resolver.ResolveNow(). The user will have no need to configure this, but
+	// we need to be able to configure this in tests.
+	resolveNowBackoff func(int) time.Duration
+}
+
+// DialOption configures how we set up the connection.
+type DialOption interface {
+	apply(*dialOptions)
+}
+
+// EmptyDialOption does not alter the dial configuration. It can be embedded in
+// another structure to build custom dial options.
+//
+// This API is EXPERIMENTAL.
+type EmptyDialOption struct{}
+
+func (EmptyDialOption) apply(*dialOptions) {}
+
+// funcDialOption wraps a function that modifies dialOptions into an
+// implementation of the DialOption interface.
+type funcDialOption struct {
+	f func(*dialOptions)
+}
+
+func (fdo *funcDialOption) apply(do *dialOptions) {
+	fdo.f(do)
+}
+
+func newFuncDialOption(f func(*dialOptions)) *funcDialOption {
+	return &funcDialOption{
+		f: f,
+	}
+}
+
+// WithWriteBufferSize determines how much data can be batched before doing a
+// write on the wire. The corresponding memory allocation for this buffer will
+// be twice the size to keep syscalls low. The default value for this buffer is
+// 32KB.
+//
+// Zero will disable the write buffer such that each write will be on underlying
+// connection. Note: A Send call may not directly translate to a write.
+func WithWriteBufferSize(s int) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.WriteBufferSize = s
+	})
+}
+
+// WithReadBufferSize lets you set the size of read buffer, this determines how
+// much data can be read at most for each read syscall.
+//
+// The default value for this buffer is 32KB. Zero will disable read buffer for
+// a connection so data framer can access the underlying conn directly.
+func WithReadBufferSize(s int) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.ReadBufferSize = s
+	})
+}
+
+// WithInitialWindowSize returns a DialOption which sets the value for initial
+// window size on a stream. The lower bound for window size is 64K and any value
+// smaller than that will be ignored.
+func WithInitialWindowSize(s int32) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.InitialWindowSize = s
+	})
+}
+
+// WithInitialConnWindowSize returns a DialOption which sets the value for
+// initial window size on a connection. The lower bound for window size is 64K
+// and any value smaller than that will be ignored.
+func WithInitialConnWindowSize(s int32) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.InitialConnWindowSize = s
+	})
+}
+
+// WithMaxMsgSize returns a DialOption which sets the maximum message size the
+// client can receive.
+//
+// Deprecated: use WithDefaultCallOptions(MaxCallRecvMsgSize(s)) instead.  Will
+// be supported throughout 1.x.
+func WithMaxMsgSize(s int) DialOption {
+	return WithDefaultCallOptions(MaxCallRecvMsgSize(s))
+}
+
+// WithDefaultCallOptions returns a DialOption which sets the default
+// CallOptions for calls over the connection.
+func WithDefaultCallOptions(cos ...CallOption) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.callOptions = append(o.callOptions, cos...)
+	})
+}
+
+// WithCodec returns a DialOption which sets a codec for message marshaling and
+// unmarshaling.
+//
+// Deprecated: use WithDefaultCallOptions(ForceCodec(_)) instead.  Will be
+// supported throughout 1.x.
+func WithCodec(c Codec) DialOption {
+	return WithDefaultCallOptions(CallCustomCodec(c))
+}
+
+// WithCompressor returns a DialOption which sets a Compressor to use for
+// message compression. It has lower priority than the compressor set by the
+// UseCompressor CallOption.
+//
+// Deprecated: use UseCompressor instead.  Will be supported throughout 1.x.
+func WithCompressor(cp Compressor) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.cp = cp
+	})
+}
+
+// WithDecompressor returns a DialOption which sets a Decompressor to use for
+// incoming message decompression.  If incoming response messages are encoded
+// using the decompressor's Type(), it will be used.  Otherwise, the message
+// encoding will be used to look up the compressor registered via
+// encoding.RegisterCompressor, which will then be used to decompress the
+// message.  If no compressor is registered for the encoding, an Unimplemented
+// status error will be returned.
+//
+// Deprecated: use encoding.RegisterCompressor instead.  Will be supported
+// throughout 1.x.
+func WithDecompressor(dc Decompressor) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.dc = dc
+	})
+}
+
+// WithBalancer returns a DialOption which sets a load balancer with the v1 API.
+// Name resolver will be ignored if this DialOption is specified.
+//
+// Deprecated: use the new balancer APIs in balancer package and
+// WithBalancerName.  Will be removed in a future 1.x release.
+func WithBalancer(b Balancer) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.balancerBuilder = &balancerWrapperBuilder{
+			b: b,
+		}
+	})
+}
+
+// WithBalancerName sets the balancer that the ClientConn will be initialized
+// with. Balancer registered with balancerName will be used. This function
+// panics if no balancer was registered by balancerName.
+//
+// The balancer cannot be overridden by balancer option specified by service
+// config.
+//
+// Deprecated: use WithDefaultServiceConfig and WithDisableServiceConfig
+// instead.  Will be removed in a future 1.x release.
+func WithBalancerName(balancerName string) DialOption {
+	builder := balancer.Get(balancerName)
+	if builder == nil {
+		panic(fmt.Sprintf("grpc.WithBalancerName: no balancer is registered for name %v", balancerName))
+	}
+	return newFuncDialOption(func(o *dialOptions) {
+		o.balancerBuilder = builder
+	})
+}
+
+// withResolverBuilder is only for grpclb.
+func withResolverBuilder(b resolver.Builder) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.resolverBuilder = b
+	})
+}
+
+// WithServiceConfig returns a DialOption which has a channel to read the
+// service configuration.
+//
+// Deprecated: service config should be received through name resolver or via
+// WithDefaultServiceConfig, as specified at
+// https://github.com/grpc/grpc/blob/master/doc/service_config.md.  Will be
+// removed in a future 1.x release.
+func WithServiceConfig(c <-chan ServiceConfig) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.scChan = c
+	})
+}
+
+// WithConnectParams configures the dialer to use the provided ConnectParams.
+//
+// The backoff configuration specified as part of the ConnectParams overrides
+// all defaults specified in
+// https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md. Consider
+// using the backoff.DefaultConfig as a base, in cases where you want to
+// override only a subset of the backoff configuration.
+//
+// This API is EXPERIMENTAL.
+func WithConnectParams(p ConnectParams) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.bs = internalbackoff.Exponential{Config: p.Backoff}
+		o.minConnectTimeout = func() time.Duration {
+			return p.MinConnectTimeout
+		}
+	})
+}
+
+// WithBackoffMaxDelay configures the dialer to use the provided maximum delay
+// when backing off after failed connection attempts.
+//
+// Deprecated: use WithConnectParams instead. Will be supported throughout 1.x.
+func WithBackoffMaxDelay(md time.Duration) DialOption {
+	return WithBackoffConfig(BackoffConfig{MaxDelay: md})
+}
+
+// WithBackoffConfig configures the dialer to use the provided backoff
+// parameters after connection failures.
+//
+// Deprecated: use WithConnectParams instead. Will be supported throughout 1.x.
+func WithBackoffConfig(b BackoffConfig) DialOption {
+	bc := backoff.DefaultConfig
+	bc.MaxDelay = b.MaxDelay
+	return withBackoff(internalbackoff.Exponential{Config: bc})
+}
+
+// withBackoff sets the backoff strategy used for connectRetryNum after a failed
+// connection attempt.
+//
+// This can be exported if arbitrary backoff strategies are allowed by gRPC.
+func withBackoff(bs internalbackoff.Strategy) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.bs = bs
+	})
+}
+
+// WithBlock returns a DialOption which makes caller of Dial blocks until the
+// underlying connection is up. Without this, Dial returns immediately and
+// connecting the server happens in background.
+func WithBlock() DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.block = true
+	})
+}
+
+// WithInsecure returns a DialOption which disables transport security for this
+// ClientConn. Note that transport security is required unless WithInsecure is
+// set.
+func WithInsecure() DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.insecure = true
+	})
+}
+
+// WithTransportCredentials returns a DialOption which configures a connection
+// level security credentials (e.g., TLS/SSL). This should not be used together
+// with WithCredentialsBundle.
+func WithTransportCredentials(creds credentials.TransportCredentials) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.TransportCredentials = creds
+	})
+}
+
+// WithPerRPCCredentials returns a DialOption which sets credentials and places
+// auth state on each outbound RPC.
+func WithPerRPCCredentials(creds credentials.PerRPCCredentials) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.PerRPCCredentials = append(o.copts.PerRPCCredentials, creds)
+	})
+}
+
+// WithCredentialsBundle returns a DialOption to set a credentials bundle for
+// the ClientConn.WithCreds. This should not be used together with
+// WithTransportCredentials.
+//
+// This API is experimental.
+func WithCredentialsBundle(b credentials.Bundle) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.CredsBundle = b
+	})
+}
+
+// WithTimeout returns a DialOption that configures a timeout for dialing a
+// ClientConn initially. This is valid if and only if WithBlock() is present.
+//
+// Deprecated: use DialContext and context.WithTimeout instead.  Will be
+// supported throughout 1.x.
+func WithTimeout(d time.Duration) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.timeout = d
+	})
+}
+
+// WithContextDialer returns a DialOption that sets a dialer to create
+// connections. If FailOnNonTempDialError() is set to true, and an error is
+// returned by f, gRPC checks the error's Temporary() method to decide if it
+// should try to reconnect to the network address.
+func WithContextDialer(f func(context.Context, string) (net.Conn, error)) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.Dialer = f
+	})
+}
+
+func init() {
+	internal.WithResolverBuilder = withResolverBuilder
+	internal.WithHealthCheckFunc = withHealthCheckFunc
+}
+
+// WithDialer returns a DialOption that specifies a function to use for dialing
+// network addresses. If FailOnNonTempDialError() is set to true, and an error
+// is returned by f, gRPC checks the error's Temporary() method to decide if it
+// should try to reconnect to the network address.
+//
+// Deprecated: use WithContextDialer instead.  Will be supported throughout
+// 1.x.
+func WithDialer(f func(string, time.Duration) (net.Conn, error)) DialOption {
+	return WithContextDialer(
+		func(ctx context.Context, addr string) (net.Conn, error) {
+			if deadline, ok := ctx.Deadline(); ok {
+				return f(addr, time.Until(deadline))
+			}
+			return f(addr, 0)
+		})
+}
+
+// WithStatsHandler returns a DialOption that specifies the stats handler for
+// all the RPCs and underlying network connections in this ClientConn.
+func WithStatsHandler(h stats.Handler) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.StatsHandler = h
+	})
+}
+
+// FailOnNonTempDialError returns a DialOption that specifies if gRPC fails on
+// non-temporary dial errors. If f is true, and dialer returns a non-temporary
+// error, gRPC will fail the connection to the network address and won't try to
+// reconnect. The default value of FailOnNonTempDialError is false.
+//
+// FailOnNonTempDialError only affects the initial dial, and does not do
+// anything useful unless you are also using WithBlock().
+//
+// This is an EXPERIMENTAL API.
+func FailOnNonTempDialError(f bool) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.FailOnNonTempDialError = f
+	})
+}
+
+// WithUserAgent returns a DialOption that specifies a user agent string for all
+// the RPCs.
+func WithUserAgent(s string) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.UserAgent = s
+	})
+}
+
+// WithKeepaliveParams returns a DialOption that specifies keepalive parameters
+// for the client transport.
+func WithKeepaliveParams(kp keepalive.ClientParameters) DialOption {
+	if kp.Time < internal.KeepaliveMinPingTime {
+		grpclog.Warningf("Adjusting keepalive ping interval to minimum period of %v", internal.KeepaliveMinPingTime)
+		kp.Time = internal.KeepaliveMinPingTime
+	}
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.KeepaliveParams = kp
+	})
+}
+
+// WithUnaryInterceptor returns a DialOption that specifies the interceptor for
+// unary RPCs.
+func WithUnaryInterceptor(f UnaryClientInterceptor) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.unaryInt = f
+	})
+}
+
+// WithChainUnaryInterceptor returns a DialOption that specifies the chained
+// interceptor for unary RPCs. The first interceptor will be the outer most,
+// while the last interceptor will be the inner most wrapper around the real call.
+// All interceptors added by this method will be chained, and the interceptor
+// defined by WithUnaryInterceptor will always be prepended to the chain.
+func WithChainUnaryInterceptor(interceptors ...UnaryClientInterceptor) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.chainUnaryInts = append(o.chainUnaryInts, interceptors...)
+	})
+}
+
+// WithStreamInterceptor returns a DialOption that specifies the interceptor for
+// streaming RPCs.
+func WithStreamInterceptor(f StreamClientInterceptor) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.streamInt = f
+	})
+}
+
+// WithChainStreamInterceptor returns a DialOption that specifies the chained
+// interceptor for unary RPCs. The first interceptor will be the outer most,
+// while the last interceptor will be the inner most wrapper around the real call.
+// All interceptors added by this method will be chained, and the interceptor
+// defined by WithStreamInterceptor will always be prepended to the chain.
+func WithChainStreamInterceptor(interceptors ...StreamClientInterceptor) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.chainStreamInts = append(o.chainStreamInts, interceptors...)
+	})
+}
+
+// WithAuthority returns a DialOption that specifies the value to be used as the
+// :authority pseudo-header. This value only works with WithInsecure and has no
+// effect if TransportCredentials are present.
+func WithAuthority(a string) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.authority = a
+	})
+}
+
+// WithChannelzParentID returns a DialOption that specifies the channelz ID of
+// current ClientConn's parent. This function is used in nested channel creation
+// (e.g. grpclb dial).
+func WithChannelzParentID(id int64) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.channelzParentID = id
+	})
+}
+
+// WithDisableServiceConfig returns a DialOption that causes gRPC to ignore any
+// service config provided by the resolver and provides a hint to the resolver
+// to not fetch service configs.
+//
+// Note that this dial option only disables service config from resolver. If
+// default service config is provided, gRPC will use the default service config.
+func WithDisableServiceConfig() DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.disableServiceConfig = true
+	})
+}
+
+// WithDefaultServiceConfig returns a DialOption that configures the default
+// service config, which will be used in cases where:
+//
+// 1. WithDisableServiceConfig is also used.
+// 2. Resolver does not return a service config or if the resolver returns an
+//    invalid service config.
+//
+// This API is EXPERIMENTAL.
+func WithDefaultServiceConfig(s string) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.defaultServiceConfigRawJSON = &s
+	})
+}
+
+// WithDisableRetry returns a DialOption that disables retries, even if the
+// service config enables them.  This does not impact transparent retries, which
+// will happen automatically if no data is written to the wire or if the RPC is
+// unprocessed by the remote server.
+//
+// Retry support is currently disabled by default, but will be enabled by
+// default in the future.  Until then, it may be enabled by setting the
+// environment variable "GRPC_GO_RETRY" to "on".
+//
+// This API is EXPERIMENTAL.
+func WithDisableRetry() DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.disableRetry = true
+	})
+}
+
+// WithMaxHeaderListSize returns a DialOption that specifies the maximum
+// (uncompressed) size of header list that the client is prepared to accept.
+func WithMaxHeaderListSize(s uint32) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.MaxHeaderListSize = &s
+	})
+}
+
+// WithDisableHealthCheck disables the LB channel health checking for all
+// SubConns of this ClientConn.
+//
+// This API is EXPERIMENTAL.
+func WithDisableHealthCheck() DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.disableHealthCheck = true
+	})
+}
+
+// withHealthCheckFunc replaces the default health check function with the
+// provided one. It makes tests easier to change the health check function.
+//
+// For testing purpose only.
+func withHealthCheckFunc(f internal.HealthChecker) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.healthCheckFunc = f
+	})
+}
+
+func defaultDialOptions() dialOptions {
+	return dialOptions{
+		disableRetry:    !envconfig.Retry,
+		healthCheckFunc: internal.HealthCheckFunc,
+		copts: transport.ConnectOptions{
+			WriteBufferSize: defaultWriteBufSize,
+			ReadBufferSize:  defaultReadBufSize,
+		},
+		resolveNowBackoff: internalbackoff.DefaultExponential.Backoff,
+	}
+}
+
+// withGetMinConnectDeadline specifies the function that clientconn uses to
+// get minConnectDeadline. This can be used to make connection attempts happen
+// faster/slower.
+//
+// For testing purpose only.
+func withMinConnectDeadline(f func() time.Duration) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.minConnectTimeout = f
+	})
+}
+
+// withResolveNowBackoff specifies the function that clientconn uses to backoff
+// between successive calls to resolver.ResolveNow().
+//
+// For testing purpose only.
+func withResolveNowBackoff(f func(int) time.Duration) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.resolveNowBackoff = f
+	})
+}