Test cases for V3 Project Actions

This submission adds a new test script "test_projects.py", so as
to verify the CRUD Operations of V3 Projects API. Required support
functions are added in client files under both XML/JSON interfaces.
Added methods to add resources (v3: users, projects, roles) in
DataGenerator class of base.py file.

Implements blueprint: add-keystone-v3-projects-tests

Change-Id: I1a0feb12e9ca503d7a03941b8e5bb1e5ae722fbc
Merge "Test cases for V3 Project Actions"