vendor: bump prometheus/client_golang v0.9.4, docker/go-metrics v0.0.1

bump docker/go-metrics v0.0.1:

full diff: docker/go-metrics@d466d4f...v0.0.1

- docker/go-metrics#16 fix the compilation error against prometheus/client-golang master
- fixes docker/go-metrics#12 No longer builds against Prom master
- docker/go-metrics#18 metrics: address compile error correctly
- fixes docker/go-metrics#12 No longer builds against Prom master
- docker/go-metrics#15 Add functions that instruments http handler using promhttp
- docker/go-metrics#20 Rename LICENSE.code → LICENSE
- docker/go-metrics#22 Support Go Modules

bump prometheus/client_golang v0.9.4:

full diff: prometheus/client_golang@c5b7fcc...v0.9.4

version v0.9.0 is the minimum required version to work with go-metrics v0.0.1,
as it depends on `prometheus.Observer`:

    vendor/github.com/docker/go-metrics/timer.go:39:4: undefined: prometheus.Observer

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Upstream-commit: b2db7c8bc967b52609877f5d856c338ea51e4c46
Component: engine

components/engine/vendor.conf

@@ -143,7 +143,7 @@ github.com/coreos/pkg                               3ac0863d7acf3bc44daf49afef89
 code.cloudfoundry.org/clock                         02e53af36e6c978af692887ed449b74026d76fec
 
 # prometheus
-github.com/prometheus/client_golang                 c5b7fccd204277076155f10851dad72b76a49317 # v0.8.0
+github.com/prometheus/client_golang                 2641b987480bca71fb39738eb8c8b0d577cb1d76 # v0.9.4
 github.com/beorn7/perks                             37c8de3658fcb183f997c4e13e8337516ab753e6 # v1.0.1
 github.com/prometheus/client_model                  d1d2010b5beead3fa1c5f271a5cf626e40b3ad6e # v0.1.0
 github.com/prometheus/common                        287d3e634a1e550c9e463dd7e5a75a422c614505 # v0.7.0
@@ -159,7 +159,7 @@ github.com/inconshreveable/mousetrap                76626ae9c91c4f2a10f34cad8ce8
 github.com/morikuni/aec                             39771216ff4c63d11f5e604076f9c45e8be1067b
 
 # metrics
-github.com/docker/go-metrics                        d466d4f6fd960e01820085bd7e1a24426ee7ef18
+github.com/docker/go-metrics                        b619b3592b65de4f087d9f16863a7e6ff905973c # v0.0.1
 
 github.com/opencontainers/selinux                   3a1f366feb7aecbf7a0e71ac4cea88b31597de9e # v1.2.2