Simple-settings

- Avoid to load python modules (as settings) in python files (with this, fix `deepcopy` bug in `as_dict()` method)[https://github.com/drgarcia1986/simple-settings/issues/14]

- Deepcopy in `as_dict` method to anticipate unexpected changes.
- Special Settings Behaviors.
- Override settings values by environment.
- Required settings validation.
- Remove default behavior of override settings values by environment (now it's a special settings).
- Settings Stub (useful for tests)
- Change bahavior of settings `__getattr__` (before may raise `KeyError` if simple-settings do not locate the setting, now raise `AttributeError`)

- Load multiple settings separated by comma (like a pipeline).
- Load settings of _cfg_ files.
- Filter python module attributes to read only user settings [https://github.com/drgarcia1986/simple-settings/issues/9].

- Fix `parser_args error` if using simple-settings with others command line arguments [https://github.com/drgarcia1986/simple-settings/issues/3]

First Release :tada: