vendor: update all dependencies except Azure SDK

The Azure SDK doesn't support Go 1.5 anymore. We can't upgrade it until
Go 1.8 comes out.

vendor/github.com/rcrowley/go-metrics/sample.go

@@ -33,7 +33,7 @@ type Sample interface {
 // priority reservoir.  See Cormode et al's "Forward Decay: A Practical Time
 // Decay Model for Streaming Systems".
 //
-// <http://www.research.att.com/people/Cormode_Graham/library/publications/CormodeShkapenyukSrivastavaXu09.pdf>
+// <http://dimacs.rutgers.edu/~graham/pubs/papers/fwddecay.pdf>
 type ExpDecaySample struct {
 	alpha         float64
 	count         int64
@@ -302,6 +302,13 @@ type SampleSnapshot struct {
 	values []int64
 }
 
+func NewSampleSnapshot(count int64, values []int64) *SampleSnapshot {
+	return &SampleSnapshot{
+		count:  count,
+		values: values,
+	}
+}
+
 // Clear panics.
 func (*SampleSnapshot) Clear() {
 	panic("Clear called on a SampleSnapshot")