requirements not automatically installed

[bjuergens]

problem

When installing csa with pip, then the dependencies matplotlib and nump must be installed manually beforehand.

Due to this problem, this package (and also all packages depending on it) can't be simply installed via requirements.txt (Example of downstream issue). This problem gets more significant if you use this package in build-pipelines where introducing extra steps always comes along with an increase in complexity.

causes

1. install_requires is not declared in setup.py
2. setup.py imports csa to read the version number, which in turn imports everything else, including matplotlib and numpy

suggested fix:

1. rename "requires" to "install_requires" in setup.py
2. hardcode version number in setup.py
3. remove version.py, since this is now unused

(I will open a PR for this)

reproduction

docker run -it ubuntu:18.04 bash
export MPLBACKEND=agg
apt-get update && apt-get install -y python-pip
pip install csa

actual behavior: The last line fails with ImportError: No module named numpy

expected behavior: No errors, because numpy and matplotlib get installed automatically

[mdjurfeldt]

Thanks---looking forward to the PR.