Add go-twitch library. (#1239)

Go client for interacting with the Twitch v3 API.

README.md

@@ -988,6 +988,7 @@ See [go-hardware](https://github.com/rakyll/go-hardware) for a comprehensive lis
 * [go-jira](https://github.com/andygrunwald/go-jira) - Go client library for [Atlassian JIRA](https://www.atlassian.com/software/jira)
 * [go-marathon](https://github.com/gambol99/go-marathon) - A Go library for interacting with Mesosphere's Marathon PAAS.
 * [go-trending](https://github.com/andygrunwald/go-trending) - Go library for accessing [trending repositories](https://github.com/trending) and [developers](https://github.com/trending/developers) at Github.
+* [go-twitch](https://github.com/knspriggs/go-twitch) - A Go client for interacting with the Twitch v3 API.
 * [go-twitter](https://github.com/dghubble/go-twitter) - Go client library for the Twitter v1.1 APIs.
 * [go-xkcd](https://github.com/nishanths/go-xkcd) - Go client for the xkcd API.
 * [goamz](https://github.com/mitchellh/goamz) - Popular fork of [goamz](https://launchpad.net/goamz) which adds some missing API calls to certain packages.