.actions should return action names

[Fryguy]

Calling .actions should just return the action names. We probably want a separate accessor for action_objects. I'm thinking that a user of the API might call actions as a browsing function, much like you can do with the github api gem. Alternately, we can keep actions as is and have a separate action_names method.

We should probably do the same thing for collections to keep them consistent.