diff --git a/vendor/golang.org/x/time/rate/rate.go b/vendor/golang.org/x/time/rate/rate.go
index 7228d97..0cfcc84 100644
--- a/vendor/golang.org/x/time/rate/rate.go
+++ b/vendor/golang.org/x/time/rate/rate.go
@@ -6,6 +6,7 @@
 package rate
 
 import (
+	"context"
 	"fmt"
 	"math"
 	"sync"
@@ -52,10 +53,9 @@
 //
 // The methods AllowN, ReserveN, and WaitN consume n tokens.
 type Limiter struct {
-	limit Limit
-	burst int
-
 	mu     sync.Mutex
+	limit  Limit
+	burst  int
 	tokens float64
 	// last is the last time the limiter's tokens field was updated
 	last time.Time
@@ -75,6 +75,8 @@
 // Burst values allow more events to happen at once.
 // A zero Burst allows no events, unless limit == Inf.
 func (lim *Limiter) Burst() int {
+	lim.mu.Lock()
+	defer lim.mu.Unlock()
 	return lim.burst
 }
 
@@ -143,7 +145,6 @@
 // Cancel is shorthand for CancelAt(time.Now()).
 func (r *Reservation) Cancel() {
 	r.CancelAt(time.Now())
-	return
 }
 
 // CancelAt indicates that the reservation holder will not perform the reserved action
@@ -184,8 +185,6 @@
 			r.lim.lastEvent = prevEvent
 		}
 	}
-
-	return
 }
 
 // Reserve is shorthand for ReserveN(time.Now(), 1).
@@ -195,7 +194,7 @@
 
 // ReserveN returns a Reservation that indicates how long the caller must wait before n events happen.
 // The Limiter takes this Reservation into account when allowing future events.
-// ReserveN returns false if n exceeds the Limiter's burst size.
+// The returned Reservation’s OK() method returns false if n exceeds the Limiter's burst size.
 // Usage example:
 //   r := lim.ReserveN(time.Now(), 1)
 //   if !r.OK() {
@@ -212,19 +211,8 @@
 	return &r
 }
 
-// contextContext is a temporary(?) copy of the context.Context type
-// to support both Go 1.6 using golang.org/x/net/context and Go 1.7+
-// with the built-in context package. If people ever stop using Go 1.6
-// we can remove this.
-type contextContext interface {
-	Deadline() (deadline time.Time, ok bool)
-	Done() <-chan struct{}
-	Err() error
-	Value(key interface{}) interface{}
-}
-
 // Wait is shorthand for WaitN(ctx, 1).
-func (lim *Limiter) wait(ctx contextContext) (err error) {
+func (lim *Limiter) Wait(ctx context.Context) (err error) {
 	return lim.WaitN(ctx, 1)
 }
 
@@ -232,9 +220,14 @@
 // It returns an error if n exceeds the Limiter's burst size, the Context is
 // canceled, or the expected wait time exceeds the Context's Deadline.
 // The burst limit is ignored if the rate limit is Inf.
-func (lim *Limiter) waitN(ctx contextContext, n int) (err error) {
-	if n > lim.burst && lim.limit != Inf {
-		return fmt.Errorf("rate: Wait(n=%d) exceeds limiter's burst %d", n, lim.burst)
+func (lim *Limiter) WaitN(ctx context.Context, n int) (err error) {
+	lim.mu.Lock()
+	burst := lim.burst
+	limit := lim.limit
+	lim.mu.Unlock()
+
+	if n > burst && limit != Inf {
+		return fmt.Errorf("rate: Wait(n=%d) exceeds limiter's burst %d", n, burst)
 	}
 	// Check if ctx is already cancelled
 	select {
@@ -291,6 +284,23 @@
 	lim.limit = newLimit
 }
 
+// SetBurst is shorthand for SetBurstAt(time.Now(), newBurst).
+func (lim *Limiter) SetBurst(newBurst int) {
+	lim.SetBurstAt(time.Now(), newBurst)
+}
+
+// SetBurstAt sets a new burst size for the limiter.
+func (lim *Limiter) SetBurstAt(now time.Time, newBurst int) {
+	lim.mu.Lock()
+	defer lim.mu.Unlock()
+
+	now, _, tokens := lim.advance(now)
+
+	lim.last = now
+	lim.tokens = tokens
+	lim.burst = newBurst
+}
+
 // reserveN is a helper method for AllowN, ReserveN, and WaitN.
 // maxFutureReserve specifies the maximum reservation wait duration allowed.
 // reserveN returns Reservation, not *Reservation, to avoid allocation in AllowN and WaitN.
@@ -347,26 +357,20 @@
 
 // advance calculates and returns an updated state for lim resulting from the passage of time.
 // lim is not changed.
+// advance requires that lim.mu is held.
 func (lim *Limiter) advance(now time.Time) (newNow time.Time, newLast time.Time, newTokens float64) {
 	last := lim.last
 	if now.Before(last) {
 		last = now
 	}
 
-	// Avoid making delta overflow below when last is very old.
-	maxElapsed := lim.limit.durationFromTokens(float64(lim.burst) - lim.tokens)
-	elapsed := now.Sub(last)
-	if elapsed > maxElapsed {
-		elapsed = maxElapsed
-	}
-
 	// Calculate the new number of tokens, due to time that passed.
+	elapsed := now.Sub(last)
 	delta := lim.limit.tokensFromDuration(elapsed)
 	tokens := lim.tokens + delta
 	if burst := float64(lim.burst); tokens > burst {
 		tokens = burst
 	}
-
 	return now, last, tokens
 }
 
@@ -374,7 +378,7 @@
 // of time it takes to accumulate them at a rate of limit tokens per second.
 func (limit Limit) durationFromTokens(tokens float64) time.Duration {
 	seconds := tokens / float64(limit)
-	return time.Nanosecond * time.Duration(1e9*seconds)
+	return time.Duration(float64(time.Second) * seconds)
 }
 
 // tokensFromDuration is a unit conversion function from a time duration to the number of tokens