Improve setup.py and dependency management

[moshthepitt]

• Use setup.py to track package dependencies.
• Make base.in read from setup.py
• Remove dependency_links from setup.py completely. This is more accurately handled in our requirement files.
• Exclude tests and docs from find_packages in setup.py
• Add setup.py module docstring
• Change package name to onadata
• Add correct version number in setup.py

Related reading:

• https://packaging.python.org/tutorials/distributing-packages/#configuring-your-project
• https://github.com/pypa/sampleproject/blob/master/setup.py

[moshthepitt]

Tests are failing because we need to add future to requirements, which is done in #1307

[pld]

sounds good, looks like tests need to be tweaked for this

[moshthepitt]

I'll update this to pull install_requires from requirements/base.in

[moshthepitt]

@ukanga after reading around, I am now completely convinced that we should not pull anything from the requirement files into setup.py

I therefore propose to move the dependencies that we have in base.in to setup.py and then change base.in and dev.in so that they can still be used to generate our respective .pip files.

Please see:

1. https://stackoverflow.com/a/19081268
2. https://caremad.io/posts/2013/07/setup-vs-requirement/
3. https://stackoverflow.com/questions/14399534/reference-requirements-txt-for-the-install-requires-kwarg-in-setuptools-setup-py#comment63662558_16624700
4. https://github.com/jazzband/pip-tools (pip-tools can work through setup.py)

[pld]

I'm happy w/this @ukanga