Add reason for ignoring the "self" rel
Flesh out first tier of RightScale resources.

Added method templates for resources that are directly available as
attributes of the RightScale class.  Each method aligns with a resource
"action" as documented in the RightScale API 1.5 reference
documentation:

    http://reference.rightscale.com/api1.5/index.html
Reimplement RightScale.run_script() with new helper objects.

This type of high-level method is probably better done in an external
script rather than as a direct method of the RightScale class.  However,
it serves as an example of how to use RightScale objects.