Python improvements

Changes
* Moves python files to a separate directory (more languages are coming)
* Merged `_helper.py` into `centroid.py` resulting in one `Config` class. Usage is `from centroid import Config`
* Changes the tests.py file to contain actual unit tests that can be ran with `python -m unittest python.tests`.
* Creates the following python API
    * `config = Config(json_str)`
    * `config = Config.from_file(filename)`
    * `config = Config.from_action(function_returning_json_str)`
    * `config = Config(json_str).environment(environment)`

Tasks
- [x] Cleanup refactoring
- [x] Cleanup commits