diff --git a/vendor/github.com/hashicorp/go-immutable-radix/iradix.go b/vendor/github.com/hashicorp/go-immutable-radix/iradix.go
new file mode 100644
index 0000000..e5e6e57
--- /dev/null
+++ b/vendor/github.com/hashicorp/go-immutable-radix/iradix.go
@@ -0,0 +1,662 @@
+package iradix
+
+import (
+	"bytes"
+	"strings"
+
+	"github.com/hashicorp/golang-lru/simplelru"
+)
+
+const (
+	// defaultModifiedCache is the default size of the modified node
+	// cache used per transaction. This is used to cache the updates
+	// to the nodes near the root, while the leaves do not need to be
+	// cached. This is important for very large transactions to prevent
+	// the modified cache from growing to be enormous. This is also used
+	// to set the max size of the mutation notify maps since those should
+	// also be bounded in a similar way.
+	defaultModifiedCache = 8192
+)
+
+// Tree implements an immutable radix tree. This can be treated as a
+// Dictionary abstract data type. The main advantage over a standard
+// hash map is prefix-based lookups and ordered iteration. The immutability
+// means that it is safe to concurrently read from a Tree without any
+// coordination.
+type Tree struct {
+	root *Node
+	size int
+}
+
+// New returns an empty Tree
+func New() *Tree {
+	t := &Tree{
+		root: &Node{
+			mutateCh: make(chan struct{}),
+		},
+	}
+	return t
+}
+
+// Len is used to return the number of elements in the tree
+func (t *Tree) Len() int {
+	return t.size
+}
+
+// Txn is a transaction on the tree. This transaction is applied
+// atomically and returns a new tree when committed. A transaction
+// is not thread safe, and should only be used by a single goroutine.
+type Txn struct {
+	// root is the modified root for the transaction.
+	root *Node
+
+	// snap is a snapshot of the root node for use if we have to run the
+	// slow notify algorithm.
+	snap *Node
+
+	// size tracks the size of the tree as it is modified during the
+	// transaction.
+	size int
+
+	// writable is a cache of writable nodes that have been created during
+	// the course of the transaction. This allows us to re-use the same
+	// nodes for further writes and avoid unnecessary copies of nodes that
+	// have never been exposed outside the transaction. This will only hold
+	// up to defaultModifiedCache number of entries.
+	writable *simplelru.LRU
+
+	// trackChannels is used to hold channels that need to be notified to
+	// signal mutation of the tree. This will only hold up to
+	// defaultModifiedCache number of entries, after which we will set the
+	// trackOverflow flag, which will cause us to use a more expensive
+	// algorithm to perform the notifications. Mutation tracking is only
+	// performed if trackMutate is true.
+	trackChannels map[chan struct{}]struct{}
+	trackOverflow bool
+	trackMutate   bool
+}
+
+// Txn starts a new transaction that can be used to mutate the tree
+func (t *Tree) Txn() *Txn {
+	txn := &Txn{
+		root: t.root,
+		snap: t.root,
+		size: t.size,
+	}
+	return txn
+}
+
+// TrackMutate can be used to toggle if mutations are tracked. If this is enabled
+// then notifications will be issued for affected internal nodes and leaves when
+// the transaction is committed.
+func (t *Txn) TrackMutate(track bool) {
+	t.trackMutate = track
+}
+
+// trackChannel safely attempts to track the given mutation channel, setting the
+// overflow flag if we can no longer track any more. This limits the amount of
+// state that will accumulate during a transaction and we have a slower algorithm
+// to switch to if we overflow.
+func (t *Txn) trackChannel(ch chan struct{}) {
+	// In overflow, make sure we don't store any more objects.
+	if t.trackOverflow {
+		return
+	}
+
+	// If this would overflow the state we reject it and set the flag (since
+	// we aren't tracking everything that's required any longer).
+	if len(t.trackChannels) >= defaultModifiedCache {
+		// Mark that we are in the overflow state
+		t.trackOverflow = true
+
+		// Clear the map so that the channels can be garbage collected. It is
+		// safe to do this since we have already overflowed and will be using
+		// the slow notify algorithm.
+		t.trackChannels = nil
+		return
+	}
+
+	// Create the map on the fly when we need it.
+	if t.trackChannels == nil {
+		t.trackChannels = make(map[chan struct{}]struct{})
+	}
+
+	// Otherwise we are good to track it.
+	t.trackChannels[ch] = struct{}{}
+}
+
+// writeNode returns a node to be modified, if the current node has already been
+// modified during the course of the transaction, it is used in-place. Set
+// forLeafUpdate to true if you are getting a write node to update the leaf,
+// which will set leaf mutation tracking appropriately as well.
+func (t *Txn) writeNode(n *Node, forLeafUpdate bool) *Node {
+	// Ensure the writable set exists.
+	if t.writable == nil {
+		lru, err := simplelru.NewLRU(defaultModifiedCache, nil)
+		if err != nil {
+			panic(err)
+		}
+		t.writable = lru
+	}
+
+	// If this node has already been modified, we can continue to use it
+	// during this transaction. We know that we don't need to track it for
+	// a node update since the node is writable, but if this is for a leaf
+	// update we track it, in case the initial write to this node didn't
+	// update the leaf.
+	if _, ok := t.writable.Get(n); ok {
+		if t.trackMutate && forLeafUpdate && n.leaf != nil {
+			t.trackChannel(n.leaf.mutateCh)
+		}
+		return n
+	}
+
+	// Mark this node as being mutated.
+	if t.trackMutate {
+		t.trackChannel(n.mutateCh)
+	}
+
+	// Mark its leaf as being mutated, if appropriate.
+	if t.trackMutate && forLeafUpdate && n.leaf != nil {
+		t.trackChannel(n.leaf.mutateCh)
+	}
+
+	// Copy the existing node. If you have set forLeafUpdate it will be
+	// safe to replace this leaf with another after you get your node for
+	// writing. You MUST replace it, because the channel associated with
+	// this leaf will be closed when this transaction is committed.
+	nc := &Node{
+		mutateCh: make(chan struct{}),
+		leaf:     n.leaf,
+	}
+	if n.prefix != nil {
+		nc.prefix = make([]byte, len(n.prefix))
+		copy(nc.prefix, n.prefix)
+	}
+	if len(n.edges) != 0 {
+		nc.edges = make([]edge, len(n.edges))
+		copy(nc.edges, n.edges)
+	}
+
+	// Mark this node as writable.
+	t.writable.Add(nc, nil)
+	return nc
+}
+
+// Visit all the nodes in the tree under n, and add their mutateChannels to the transaction
+// Returns the size of the subtree visited
+func (t *Txn) trackChannelsAndCount(n *Node) int {
+	// Count only leaf nodes
+	leaves := 0
+	if n.leaf != nil {
+		leaves = 1
+	}
+	// Mark this node as being mutated.
+	if t.trackMutate {
+		t.trackChannel(n.mutateCh)
+	}
+
+	// Mark its leaf as being mutated, if appropriate.
+	if t.trackMutate && n.leaf != nil {
+		t.trackChannel(n.leaf.mutateCh)
+	}
+
+	// Recurse on the children
+	for _, e := range n.edges {
+		leaves += t.trackChannelsAndCount(e.node)
+	}
+	return leaves
+}
+
+// mergeChild is called to collapse the given node with its child. This is only
+// called when the given node is not a leaf and has a single edge.
+func (t *Txn) mergeChild(n *Node) {
+	// Mark the child node as being mutated since we are about to abandon
+	// it. We don't need to mark the leaf since we are retaining it if it
+	// is there.
+	e := n.edges[0]
+	child := e.node
+	if t.trackMutate {
+		t.trackChannel(child.mutateCh)
+	}
+
+	// Merge the nodes.
+	n.prefix = concat(n.prefix, child.prefix)
+	n.leaf = child.leaf
+	if len(child.edges) != 0 {
+		n.edges = make([]edge, len(child.edges))
+		copy(n.edges, child.edges)
+	} else {
+		n.edges = nil
+	}
+}
+
+// insert does a recursive insertion
+func (t *Txn) insert(n *Node, k, search []byte, v interface{}) (*Node, interface{}, bool) {
+	// Handle key exhaustion
+	if len(search) == 0 {
+		var oldVal interface{}
+		didUpdate := false
+		if n.isLeaf() {
+			oldVal = n.leaf.val
+			didUpdate = true
+		}
+
+		nc := t.writeNode(n, true)
+		nc.leaf = &leafNode{
+			mutateCh: make(chan struct{}),
+			key:      k,
+			val:      v,
+		}
+		return nc, oldVal, didUpdate
+	}
+
+	// Look for the edge
+	idx, child := n.getEdge(search[0])
+
+	// No edge, create one
+	if child == nil {
+		e := edge{
+			label: search[0],
+			node: &Node{
+				mutateCh: make(chan struct{}),
+				leaf: &leafNode{
+					mutateCh: make(chan struct{}),
+					key:      k,
+					val:      v,
+				},
+				prefix: search,
+			},
+		}
+		nc := t.writeNode(n, false)
+		nc.addEdge(e)
+		return nc, nil, false
+	}
+
+	// Determine longest prefix of the search key on match
+	commonPrefix := longestPrefix(search, child.prefix)
+	if commonPrefix == len(child.prefix) {
+		search = search[commonPrefix:]
+		newChild, oldVal, didUpdate := t.insert(child, k, search, v)
+		if newChild != nil {
+			nc := t.writeNode(n, false)
+			nc.edges[idx].node = newChild
+			return nc, oldVal, didUpdate
+		}
+		return nil, oldVal, didUpdate
+	}
+
+	// Split the node
+	nc := t.writeNode(n, false)
+	splitNode := &Node{
+		mutateCh: make(chan struct{}),
+		prefix:   search[:commonPrefix],
+	}
+	nc.replaceEdge(edge{
+		label: search[0],
+		node:  splitNode,
+	})
+
+	// Restore the existing child node
+	modChild := t.writeNode(child, false)
+	splitNode.addEdge(edge{
+		label: modChild.prefix[commonPrefix],
+		node:  modChild,
+	})
+	modChild.prefix = modChild.prefix[commonPrefix:]
+
+	// Create a new leaf node
+	leaf := &leafNode{
+		mutateCh: make(chan struct{}),
+		key:      k,
+		val:      v,
+	}
+
+	// If the new key is a subset, add to to this node
+	search = search[commonPrefix:]
+	if len(search) == 0 {
+		splitNode.leaf = leaf
+		return nc, nil, false
+	}
+
+	// Create a new edge for the node
+	splitNode.addEdge(edge{
+		label: search[0],
+		node: &Node{
+			mutateCh: make(chan struct{}),
+			leaf:     leaf,
+			prefix:   search,
+		},
+	})
+	return nc, nil, false
+}
+
+// delete does a recursive deletion
+func (t *Txn) delete(parent, n *Node, search []byte) (*Node, *leafNode) {
+	// Check for key exhaustion
+	if len(search) == 0 {
+		if !n.isLeaf() {
+			return nil, nil
+		}
+		// Copy the pointer in case we are in a transaction that already
+		// modified this node since the node will be reused. Any changes
+		// made to the node will not affect returning the original leaf
+		// value.
+		oldLeaf := n.leaf
+
+		// Remove the leaf node
+		nc := t.writeNode(n, true)
+		nc.leaf = nil
+
+		// Check if this node should be merged
+		if n != t.root && len(nc.edges) == 1 {
+			t.mergeChild(nc)
+		}
+		return nc, oldLeaf
+	}
+
+	// Look for an edge
+	label := search[0]
+	idx, child := n.getEdge(label)
+	if child == nil || !bytes.HasPrefix(search, child.prefix) {
+		return nil, nil
+	}
+
+	// Consume the search prefix
+	search = search[len(child.prefix):]
+	newChild, leaf := t.delete(n, child, search)
+	if newChild == nil {
+		return nil, nil
+	}
+
+	// Copy this node. WATCH OUT - it's safe to pass "false" here because we
+	// will only ADD a leaf via nc.mergeChild() if there isn't one due to
+	// the !nc.isLeaf() check in the logic just below. This is pretty subtle,
+	// so be careful if you change any of the logic here.
+	nc := t.writeNode(n, false)
+
+	// Delete the edge if the node has no edges
+	if newChild.leaf == nil && len(newChild.edges) == 0 {
+		nc.delEdge(label)
+		if n != t.root && len(nc.edges) == 1 && !nc.isLeaf() {
+			t.mergeChild(nc)
+		}
+	} else {
+		nc.edges[idx].node = newChild
+	}
+	return nc, leaf
+}
+
+// delete does a recursive deletion
+func (t *Txn) deletePrefix(parent, n *Node, search []byte) (*Node, int) {
+	// Check for key exhaustion
+	if len(search) == 0 {
+		nc := t.writeNode(n, true)
+		if n.isLeaf() {
+			nc.leaf = nil
+		}
+		nc.edges = nil
+		return nc, t.trackChannelsAndCount(n)
+	}
+
+	// Look for an edge
+	label := search[0]
+	idx, child := n.getEdge(label)
+	// We make sure that either the child node's prefix starts with the search term, or the search term starts with the child node's prefix
+	// Need to do both so that we can delete prefixes that don't correspond to any node in the tree
+	if child == nil || (!bytes.HasPrefix(child.prefix, search) && !bytes.HasPrefix(search, child.prefix)) {
+		return nil, 0
+	}
+
+	// Consume the search prefix
+	if len(child.prefix) > len(search) {
+		search = []byte("")
+	} else {
+		search = search[len(child.prefix):]
+	}
+	newChild, numDeletions := t.deletePrefix(n, child, search)
+	if newChild == nil {
+		return nil, 0
+	}
+	// Copy this node. WATCH OUT - it's safe to pass "false" here because we
+	// will only ADD a leaf via nc.mergeChild() if there isn't one due to
+	// the !nc.isLeaf() check in the logic just below. This is pretty subtle,
+	// so be careful if you change any of the logic here.
+
+	nc := t.writeNode(n, false)
+
+	// Delete the edge if the node has no edges
+	if newChild.leaf == nil && len(newChild.edges) == 0 {
+		nc.delEdge(label)
+		if n != t.root && len(nc.edges) == 1 && !nc.isLeaf() {
+			t.mergeChild(nc)
+		}
+	} else {
+		nc.edges[idx].node = newChild
+	}
+	return nc, numDeletions
+}
+
+// Insert is used to add or update a given key. The return provides
+// the previous value and a bool indicating if any was set.
+func (t *Txn) Insert(k []byte, v interface{}) (interface{}, bool) {
+	newRoot, oldVal, didUpdate := t.insert(t.root, k, k, v)
+	if newRoot != nil {
+		t.root = newRoot
+	}
+	if !didUpdate {
+		t.size++
+	}
+	return oldVal, didUpdate
+}
+
+// Delete is used to delete a given key. Returns the old value if any,
+// and a bool indicating if the key was set.
+func (t *Txn) Delete(k []byte) (interface{}, bool) {
+	newRoot, leaf := t.delete(nil, t.root, k)
+	if newRoot != nil {
+		t.root = newRoot
+	}
+	if leaf != nil {
+		t.size--
+		return leaf.val, true
+	}
+	return nil, false
+}
+
+// DeletePrefix is used to delete an entire subtree that matches the prefix
+// This will delete all nodes under that prefix
+func (t *Txn) DeletePrefix(prefix []byte) bool {
+	newRoot, numDeletions := t.deletePrefix(nil, t.root, prefix)
+	if newRoot != nil {
+		t.root = newRoot
+		t.size = t.size - numDeletions
+		return true
+	}
+	return false
+
+}
+
+// Root returns the current root of the radix tree within this
+// transaction. The root is not safe across insert and delete operations,
+// but can be used to read the current state during a transaction.
+func (t *Txn) Root() *Node {
+	return t.root
+}
+
+// Get is used to lookup a specific key, returning
+// the value and if it was found
+func (t *Txn) Get(k []byte) (interface{}, bool) {
+	return t.root.Get(k)
+}
+
+// GetWatch is used to lookup a specific key, returning
+// the watch channel, value and if it was found
+func (t *Txn) GetWatch(k []byte) (<-chan struct{}, interface{}, bool) {
+	return t.root.GetWatch(k)
+}
+
+// Commit is used to finalize the transaction and return a new tree. If mutation
+// tracking is turned on then notifications will also be issued.
+func (t *Txn) Commit() *Tree {
+	nt := t.CommitOnly()
+	if t.trackMutate {
+		t.Notify()
+	}
+	return nt
+}
+
+// CommitOnly is used to finalize the transaction and return a new tree, but
+// does not issue any notifications until Notify is called.
+func (t *Txn) CommitOnly() *Tree {
+	nt := &Tree{t.root, t.size}
+	t.writable = nil
+	return nt
+}
+
+// slowNotify does a complete comparison of the before and after trees in order
+// to trigger notifications. This doesn't require any additional state but it
+// is very expensive to compute.
+func (t *Txn) slowNotify() {
+	snapIter := t.snap.rawIterator()
+	rootIter := t.root.rawIterator()
+	for snapIter.Front() != nil || rootIter.Front() != nil {
+		// If we've exhausted the nodes in the old snapshot, we know
+		// there's nothing remaining to notify.
+		if snapIter.Front() == nil {
+			return
+		}
+		snapElem := snapIter.Front()
+
+		// If we've exhausted the nodes in the new root, we know we need
+		// to invalidate everything that remains in the old snapshot. We
+		// know from the loop condition there's something in the old
+		// snapshot.
+		if rootIter.Front() == nil {
+			close(snapElem.mutateCh)
+			if snapElem.isLeaf() {
+				close(snapElem.leaf.mutateCh)
+			}
+			snapIter.Next()
+			continue
+		}
+
+		// Do one string compare so we can check the various conditions
+		// below without repeating the compare.
+		cmp := strings.Compare(snapIter.Path(), rootIter.Path())
+
+		// If the snapshot is behind the root, then we must have deleted
+		// this node during the transaction.
+		if cmp < 0 {
+			close(snapElem.mutateCh)
+			if snapElem.isLeaf() {
+				close(snapElem.leaf.mutateCh)
+			}
+			snapIter.Next()
+			continue
+		}
+
+		// If the snapshot is ahead of the root, then we must have added
+		// this node during the transaction.
+		if cmp > 0 {
+			rootIter.Next()
+			continue
+		}
+
+		// If we have the same path, then we need to see if we mutated a
+		// node and possibly the leaf.
+		rootElem := rootIter.Front()
+		if snapElem != rootElem {
+			close(snapElem.mutateCh)
+			if snapElem.leaf != nil && (snapElem.leaf != rootElem.leaf) {
+				close(snapElem.leaf.mutateCh)
+			}
+		}
+		snapIter.Next()
+		rootIter.Next()
+	}
+}
+
+// Notify is used along with TrackMutate to trigger notifications. This must
+// only be done once a transaction is committed via CommitOnly, and it is called
+// automatically by Commit.
+func (t *Txn) Notify() {
+	if !t.trackMutate {
+		return
+	}
+
+	// If we've overflowed the tracking state we can't use it in any way and
+	// need to do a full tree compare.
+	if t.trackOverflow {
+		t.slowNotify()
+	} else {
+		for ch := range t.trackChannels {
+			close(ch)
+		}
+	}
+
+	// Clean up the tracking state so that a re-notify is safe (will trigger
+	// the else clause above which will be a no-op).
+	t.trackChannels = nil
+	t.trackOverflow = false
+}
+
+// Insert is used to add or update a given key. The return provides
+// the new tree, previous value and a bool indicating if any was set.
+func (t *Tree) Insert(k []byte, v interface{}) (*Tree, interface{}, bool) {
+	txn := t.Txn()
+	old, ok := txn.Insert(k, v)
+	return txn.Commit(), old, ok
+}
+
+// Delete is used to delete a given key. Returns the new tree,
+// old value if any, and a bool indicating if the key was set.
+func (t *Tree) Delete(k []byte) (*Tree, interface{}, bool) {
+	txn := t.Txn()
+	old, ok := txn.Delete(k)
+	return txn.Commit(), old, ok
+}
+
+// DeletePrefix is used to delete all nodes starting with a given prefix. Returns the new tree,
+// and a bool indicating if the prefix matched any nodes
+func (t *Tree) DeletePrefix(k []byte) (*Tree, bool) {
+	txn := t.Txn()
+	ok := txn.DeletePrefix(k)
+	return txn.Commit(), ok
+}
+
+// Root returns the root node of the tree which can be used for richer
+// query operations.
+func (t *Tree) Root() *Node {
+	return t.root
+}
+
+// Get is used to lookup a specific key, returning
+// the value and if it was found
+func (t *Tree) Get(k []byte) (interface{}, bool) {
+	return t.root.Get(k)
+}
+
+// longestPrefix finds the length of the shared prefix
+// of two strings
+func longestPrefix(k1, k2 []byte) int {
+	max := len(k1)
+	if l := len(k2); l < max {
+		max = l
+	}
+	var i int
+	for i = 0; i < max; i++ {
+		if k1[i] != k2[i] {
+			break
+		}
+	}
+	return i
+}
+
+// concat two byte slices, returning a third new copy
+func concat(a, b []byte) []byte {
+	c := make([]byte, len(a)+len(b))
+	copy(c, a)
+	copy(c[len(a):], b)
+	return c
+}