Add acceptance test for Removing Group Membership

Add automated acceptance tests for Removing Group Membership test cases.

Acceptance/Build validation test (testNG group=smoke):
1. remove client's membership from existing group.

Test case:

Additional functional group test that can be added as part of this task or split into a different task (testNG group=functional):

test cases MIFOSTEST-46, MIFOSTEST-47, and throught MIFOSTEST-53.