Update vendored dependencies

Ran 'go mod vendor'

vendor/modules.txt

@@ -0,0 +1,43 @@
+# github.com/beorn7/perks v0.0.0-20160229213445-3ac7bf7a47d1
+## explicit
+github.com/beorn7/perks/quantile
+# github.com/davecgh/go-spew v1.0.1-0.20160907170601-6d212800a42e
+## explicit
+github.com/davecgh/go-spew/spew
+# github.com/golang/mock v0.0.0-20160127222235-bd3c8e81be01
+## explicit
+github.com/golang/mock/gomock
+# github.com/golang/protobuf v0.0.0-20160629211053-3852dcfda249
+## explicit
+github.com/golang/protobuf/proto
+# github.com/kr/fs v0.1.0
+## explicit
+# github.com/kr/pretty v0.2.1
+## explicit
+# github.com/matttproud/golang_protobuf_extensions v1.0.1
+## explicit
+github.com/matttproud/golang_protobuf_extensions/pbutil
+# github.com/pmezard/go-difflib v1.0.0
+## explicit
+github.com/pmezard/go-difflib/difflib
+# github.com/prometheus/client_golang v0.0.0-20160627143620-9f1ed1ed4a5f
+## explicit
+github.com/prometheus/client_golang/prometheus
+# github.com/prometheus/client_model v0.0.0-20150212101744-fa8ad6fec335
+## explicit
+github.com/prometheus/client_model/go
+# github.com/prometheus/common v0.0.0-20160623151427-4402f4e5ea79
+## explicit
+github.com/prometheus/common/expfmt
+github.com/prometheus/common/internal/bitbucket.org/ww/goautoneg
+github.com/prometheus/common/model
+# github.com/prometheus/procfs v0.0.0-20160411190841-abf152e5f3e9
+## explicit
+github.com/prometheus/procfs
+# github.com/stretchr/testify v1.1.5-0.20160925220609-976c720a22c8
+## explicit
+github.com/stretchr/testify/assert
+# github.com/tools/godep v0.0.0-20180126220526-ce0bfadeb516
+## explicit
+# golang.org/x/tools v0.1.5
+## explicit