Changed docs to use RTD theme
Added django-taggit:
 * a fixture with some tags.
 * Downgraded and version locked the django_comments dependency
Added documentation for tags support
 * Updated install-usage and features listing
 * Added missing sphinx rtd dependency to tox
 * Added history under new 'tip' section
  * (copied convention from markitup)
Merge pull request #11 from WimpyAnalytics/categories

tags