enabling trove to work in multi-region deployment

In a multi-region environment with trove in both, troveclient
currently throws an error regarding ambiguous endpoints if a
region_name kwarg is not passed in. Now passing in the
services_region.

Change-Id: I0a2cea3d532680549a594e8bf0e9df1d15f37cde
Closes-bug: #1227888
Merge "enabling trove to work in multi-region deployment"