Added ResourceObject.refresh(subresname) for explicit re-retrieve.

This means the user has to call res.refresh(subres) if they need to guarentee that the sub-resources of a resource they're working with is up to date.
Ideally, the resource would update its sub-resources whenever a change occurs, but that introduces huge complications; even when not considering external agents altering data, the way the client is built makes it very complicated to keep track of what ResourceObjects, etc, need to be notified in the case of any change (create/update/delete).
setup.py details added
Rewrote to use session (tests all broke)
Messing with tests; checking if vcrpy works with Session
Kwargs for connection.get; / in connection methods is now optional
Changed get_all to iter_all; Added get_all, returning list instead of generator
Moved httpexceptions out; Connection wraps result dicts in Mapping for dot access
Changed Mapping wrap to be opt-out (Client opts out)
Forgot to add. Previous commit.
Changes (minor) to Connection to better support OAuth
Added OAuthConnection class; helps registration & makes requests
Corrected dependencies in setup.py
Update README.md
Merge pull request #4 from bc-jackiehuynh/oauth2

OAuth2 (and some other random stuff)