Refactor as package

[kaczmarj]

This pull request proposes the following changes:

• move all of the python files into a tfomics module
• add setup.py file to enable installation with pip

to try it out, you can install my branch:

pip install --no-cache-dir https://github.com/kaczmarj/tfomics/tarball/refactor-as-package
pip install --no-cache-dir tensorflow

I did not include tensorflow in the list of dependencies because I can imagine someone wanting tensorflow-cpu vs tensorflow or perhaps some other tensorflow installation.