This patch is primarily a refactor to make the validate-modules arg-spec
no longer generate a traceback. It additionally includes removal of deprecated
code in the virtual server module.
* 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'