Clinner

* Use poetry for handling packaging and requirements.
* Integrate black as code formatter.
* Integrate flake8 as code linter.
* Integrate isort as import formatter.
* Replace tox previous tasks to use black, flake8 and isort.
* New command for running black.
* New command for running flake8.
* New command for running isort.

* Adds long description to setup.

* Update setup.py to avoid dependencies and use Pipfile instead of requirements.txt

* SIGINT handler for shell commands.

* Compatible with Python 3.5

* Refactor test to remove TestCase inheritance and use purely pytest.
* Add inputs module with some functions for asking user data.