Adds new v3 projects tests to Keystone

This submission adds a new test script "test_list_projects.py"
which has list projects with filters test cases. Also adds
missing v2 tests in v3 projects test script. Hence made
required changes in support functions too. As there is a new
script test_list_projects.py with list cases in it, hence removed
the test_list_projects test case from test_projects.py script and
added it to test_list_projects.py

Change-Id: I2db83e7cb70d89e7516c92eba4cb24115203e143
Merge "Adds new v3 projects tests to Keystone"