Dataflake-cache

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- use pkgutil-style namespace declaration
- package cleanup (``.gitignore``, ``MANIFEST.in``, ``README.rst``)
- docs cleanup (``Makefile``, ``conf.py``)
- tests cleanup (``tox.ini``, ``.travis.yml``)
- remove unsupported documentation bits
- fix coverage tests to only test this package
- remove coveralls from the Travis CI configuration

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- added pypy3 to the tested tox environments
- added ``flake8`` PEP 8 testing to tox configuration
- PEP 8 code cleanup

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- move code and issue tracking to GitHub
- move documentation to readthedocs

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- Update bootstrap script and test with later Python versions

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- change test code to work under Python 2 and Python 3 in order
to drop any 2to3 dependency.
- moving from ``zope.interface.implements`` to the decorator
function ``zope.interface.implementer`` which is supported in
Python 3 without the need for the ``zope.fixers`` 2to3
plugin. The decorator syntax means dropping support for
Python 2.4 and 2.5, though.
- add Jython to the supported Python implementations