API V2 proposal.

I'm working on a new command line tool for addons, and i need some additional api calls. I've implemented them as a new version. Hope it can get merged in. 

It implements the following calls:

/api/v2/addons - returns all addons
/api/v2/addon/:name - returns specific addon based on a name
/api/v2/addon/:owner/:addon - returns specific addon based on owner and name