Trying to turn this into a real plugin

Hey Gentlemen,

I haven't actually tested this, because it seems you are using Java 7 syntax and the default cordova-cli build does not.  Either way, I don't have the CC SDK setup or whatever.

After this restructuring I could do `cordova plugin add ~/.../cordova-chromecast` and it adds fine.  Perhaps you would like to test?

Its actually a bit of a pain to iterate on development when plugins are installed this way, but I can give some tips.  Let me know if it works first, will ya?