Test cases for Endpoints V3 API

Adds a test script "test_endpoints.py" so as to test CREATE, DELETE,
LIST, UPDATE API actions. endpoints_client.py is added with all the required
methods. Implementation done in JSON and XML interfaces.

Implements: blueprint keystone-v3-endpoints-api-test

Change-Id: Icd47728d161d440440f6b4f103a55125da8bbf29
10 files changed