args.py: Removed subcommand requirement

args.parse_args would exit if a subcommand wasn't specified. With the
refactored configuration system being in config.init and calling this
function to setup tests, this no longer is an ideal solution.
logger.py: Remove mode check in _logger

When running tests without apc.conf, this would cause the tests to fail. Some
other solution will have to be found, or none at all.
Remove tests_app.py

The existing tests have been moved to test_config.py. Currently, app.py has
nothing of importance to test.
Return py.path instead of string
Deleted unused files
Refactor tests to properly use test fixtures
Make arg path in locate_in_path required
The save/load funcs are now able to use specific paths

In order to cleanly test saving and loading config.yamls, it became necessary
to save and load from a specific path, not just a project path.
Finish test refactor

All tests now use pytest.fixture for decreased boilerplate code and improved
readability.