Releases and or tag go-metrics

[ryanmcnamara]

Would you consider releasing or tagging go-metrics?

We use dep and a lack of tags makes it slightly hard to work with this library (we are forced to specify the "develop" branch as a dependency, since specifying commit hashes is deprecated, I believe as an effort to promote tagging in the go community)

[lalib]

Could you please consider releasing a version? @rcrowley

[jpreese]

Would also be interested in seeing a tag for this