adding win_groupadd unit test case.

[jayeshka]

Implemented win_groupadd_test unit test case.

[jayeshka]

Lot many changes on 2015.5 branch.
Will fix this first.

[jfindlay]

@jayeshka, while we can't mock modules using patch, unit tests that rely on external libraries should be written as if that library is available because if you don't use patch and the way that python unittest works, replacing an object for a test will persist beyond the scope of that test. Instead you may do something like

...
try:
    import win_lib
    HAS_WIN_LIB = True
except ImportError:
    HAS_WIN_LIB = False
...
@skipIf(not HAS_WIN_LIB, 'these tests can only run with win_lib installed')
class WinLibTestCase(TestCase):
...

Is it possible for you to rewrite this test in this case? I think it should be mostly just removing the mock classes and adding the necessary imports. Thanks.

[jayeshka]

Will fix this.
Thanks @jfindlay