Fix setup_test_v3_user method in identity base.py

Create user in v3 identity json/xml only has two parameters.
To test the fixing, I add a v3 user test :
- test_get_user

Change-Id: I2168a21f361e0ed83b91de06652bfeea424f92f6
Merge "Fix setup_test_v3_user method in identity base.py"