* move set_module_args to units.modules.utils
* unit tests: reuse set_module_args
* unit tests: mock exit/fail_json in module.utils.ModuleTestCase
* unit tests: use module.utils.ModuleTestCase
* unit tests: fix 'import shadowed by loop variable'
New conventions for ansible warrant fixes to accomodate those
in bigip_partition.
This patch also includes an import fix that can raise an error when
Ansible unit tests run
