Tests are not part of the core logic of Hyde, and they should not be
packaged as such.

- Update changelog
- Relax dependency version requirements
- Update readme
- Read setup.py requirements from requirements text files

Distribute is deprecated; setuptools is now the recommended
packaging library.

Fixes #253, fixes #286

- Add LICENSE, AUTHORS.rst, CHANGELOG.rst and README.rst to MANIFEST.in.
- Add "Hyde contributors" to copyright.