Added support for Plex Web Player version 2.
Merge branch 'master' into plex

Conflicts:
	extension/manifest.json
Updated extension for Plex Player version 2.2.7 and keysocket 0.5.0.
Added Plex to the list of supported sites in README.
Fixed copypasta stop button variable name.
Merge pull request #35 from nolsto/plex

Add support for Plex