Botibal

Additions:
- [botibal] spontaneous factorial computation
- [docs] Add Sphinx doncumentation
- [tests] run everything with Tox
- [python] Python 3.5 support

Deletions:
- [make] test targets (Tox is love!)
- [python] drop Python 2.7 support

Modifications:
- [reqs] update dependencies

Fix:
- do not attempt to generate universal wheels

Changes:
- [readme] update badges

Changes:
- [pypi] prepare sources for packaging
- [tests] add Tox configuration

Modifications:
- Python 3.4 / SliXMPP support
- improve packaging
- console script entrypoint
- Makefile targets
- cleanup / fix lint errors

Modifications:
- code cleanup
- improve lint: PEP257, PEP8, Pylint
- improve packaging