adds support for configurations management

Reason:
Adding configuration group support for the python-troveclient

Changes:
adding configuration api calls
adding the compat client for tests and xml
added the shell cmds for the configurations in the client
made the path to datastore/version/parameters
added unit tests

partially implements blueprint configuration-management

Change-Id: Ifc0b4077c93a805898b4cd157e33172f64e85b55