Dataflake.docbuilder

-----------------
- added tox configuration to do PEP-8 checking with ``flake8``
- PEP 8 code cleanup

-----------------
- If output folders don't exist yet create them instead of failing.
- Use the name ``development`` instead of ``trunk`` or ``head`` to
designate the current development version in the rendered index page.
- If a version control URL does not specify which version control
system is used, `Git` is now used as default instead of `Subversion`.
- Moved the repository to GitHub and its documentation to ReadTheDocs

-----------------
- added flag ``-c``/``--copy-output`` which will copy instead of link
all HTML output into the folder designated as HTML output folder.

-----------------
- switched documentation to point to the new Git repository
- use new bootstrap.py script

-----------------
- Add a flag ``-m``/``--max-tags`` to set the number of package
versions (tags) to be shown on the generated main page. If more
tags exist, a link to a separate page is provided that shows all
versions.

-----------------
- Catch additional errors upon building
- Ignoring empty tag lists when asking Git for tags