Committing new RSAPI Exception

New exception for RightScale API errors... extended Exception() with a
few extra properties--no big deal.  Finalized IPAddress class, working
on IPAddress unit tests, though it's a little tough to actually perform
tests without an internet connection from JFK...
Updating Session obj and little tweaks

Updates to naming to RSObjectBase and Utility.  Session object defined,
not sure how we're going to use it b/c a lot of it's login stuff that's
handled centrally via the APIClient.Instance singleton authentication
methods
moving some stuff around

refs#26
moving RSAPI Exception and playing around with file structure