Take region_name into account when calling url_for

Fixes bug 1103282

When creating a Client object with region_name specified, url_for
will return an endpoint url for that region.

Change-Id: Ia5c95503fe2ed5e53de93040d70ba08a9c09f286
Merge "Take region_name into account when calling url_for"
fix discrepancies seen in domain and credential, v3 - bug 1109349

domains.py
added list method
added args private_project_names and private_user_names to create and update
credentials.py
added list method

Change-Id: I0d231e909742bb56b79c91d3d0f7dac3bd3ec552