Add docker as possible environment for development

[AdamStrojek]

I have created basic structure that helps in developing project using Docker. Some IDE allows to use Docker image as Python interpreter. This allow to start everyone start developing code in no time

[danielkza]

Hi Adam, sorry for the delay on getting to this.

Overall I love the idea of setting up a Docker dev-env, but I have a few reservations over the approach.

a) Seeing a Dockerfile in the root of the repository creates the expectation that there is an image that you can use for actually running cassandra-migrate, not just developing it, and that is yet not the case.
b) It's much easier to develop by mounting the code folder instead of copying it and rebuilding the image every time. Since there's no .dockerignore file, it will also pull a local virtualenv if you have one and lots of extraneous files. docker-compose works better for that case, and will also allow you to easily spin up a Cassandra instance for testing.
c) I don't like having to maintain an author list. The git history does that job much better.

I understand if you don't have the time to work on all this; in that case, I'll get to it in the near future.

Thank you very much for your contribution either way :)