Crunchyroll plugin

First of all, thank you again for your support on the IRC channel, really helped me out to refine the plugin.

Ok now: I made this plugin to be able to access [Crunchyroll](http://www.crunchyroll.com)'s videos through livestreamer. It's based on [this](https://github.com/MattRK/Crunchyroll.bundle) Plex plugin from where I took most of the logic and API calls.

One point that may be of concern: the API isn't really "public", as far as I'm concerned Crunchyroll uses it for their own applications on some devices (PS3, Xbox, Android, IOS and others). The plugin uses custom headers an a API token to try to pass as a PS3 console.

Please check it out and consider to merge the plugin into the codebase.
Let me know if I should review something or if you need me to squash the commits.