* 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'
* Extend tests to have multiple device representations
* Move filepath munging to nxos_module
* Device needs to be kwarg so we can leave it off
* Update other nxos tests
* Update tests that fell through
