Feature heroku api v3

Due to the changes in the API at Heroku, I haven't made any effort to make this version backwards compatible. I bumped the version to 3.0.0 to align with the API itself. 

I've fleshed out pretty much all of the functionality on offer from the Heroku API except the OAuth. 

I'll be rolling this code into one of my own production projects, so it should get some live testing shortly...