Massive changes to Flask-FlatPages, preparing to 0.4 release:

* Implement ``FLATPAGES_MARKDOWN_EXTENSIONS`` config.
* Several PEP8 fixes.
* Fixes to tests to run on Mac OS X.
Update docs to cover latest changes.
Bump version number.
Fixes for Python 2.5.
Fix version number :)
Last fix in ``setup.py`` before final 0.4 release.
Fix typo while importing Pygments ``HtmlFormatter``, add test to checking ``pygments_style_defs`` function output, updates to tox and travis configurations.
Revert "Add support for defining FLATPAGES_HTML_RENDERER on a per flat page basis."

This reverts commit 24718efa966c493844f0d4747c7b45ee140cb64a.
Merge remote-tracking branch 'upstream/master'