add gcm to Third-party APIs

README.md

@@ -775,6 +775,7 @@ See [go-hardware](https://github.com/rakyll/go-hardware) for a comprehensive lis
 * [facebook](https://github.com/huandu/facebook) - Go Library that supports the Facebook Graph API
 * [gads](https://github.com/emiddleton/gads) - Google Adwords Unofficial API
 * [gami](https://github.com/bit4bit/gami) - Go library for Asterisk Manager Interface.
+* [gcm](https://github.com/Aorioli/gcm) - Go library for Google Cloud Messaging
 * [geo-golang](https://github.com/codingsince1985/geo-golang) - Go Library to access [Google Maps](https://developers.google.com/maps/documentation/geocoding/intro), [MapQuest](http://open.mapquestapi.com/geocoding/), [Nominatim](http://open.mapquestapi.com/nominatim/), [OpenCage](http://geocoder.opencagedata.com/api.html), [HERE](https://developer.here.com/rest-apis/documentation/geocoder) and [Bing](https://msdn.microsoft.com/en-us/library/ff701715.aspx) geocoding / reverse geocoding APIs.
 * [ghost](https://github.com/neuegram/ghost) - Go Library for accessing the Snapchat API.
 * [github](https://github.com/google/go-github) - Go library for accessing the GitHub API.