Move action templates to their own module.

The rightscale.py module was getting large.  Besides, the template data
that is used to create methods deserves its own home.
Use RS_REST_ACTIONS directly.

Instead of binding the action templates as attributes of RightScale
objects, just use them.  There's nothing to be gained from them being
part of the state of an instance.
Clean up some path and naming inconsistencies.

Some paths were set unnecessarily as instance members.  Also,
s/RESTOAuthClient/HTTPClient/ because that's really what it has become.