Move to Pipfile for dependencies management

[mykola-mokhnach]

Currently the module dependencies are managed by requirements.txt. This is not good, since such format does not provide good compatibility with multiple python versions and also does not allow to properly use dependencies lock approach. We need to switch deps management to use Pipfile, which is actively developed and has much more possibilities for fine-tuning

[KazuCocoa]

nice 👍

[ki4070ma]

Just introduced pipfile by #376.

We need to utilize pipfile function on demands in the future.
e.g. https://github.com/pypa/pipfile/blob/master/examples/Pipfile