Allow to specify a related_name to enable multiple tagging relations on one model.

This is pretty barebone for now, but should work till a nice solution is found
(Model validation in Django is stricter than it needs to be :/).
Added support for prefetch_related on tags fields
added IDE to ignore
Made test python 2.6 compliant and removed gitignore item
more py 2.6 compliance
python 3.2 compatability
break some lines to match the 80 characters rule
added changelog
django 1.7 compatability
Merge pull request #140 from idanz/develop

Added support for prefetch_related on tag fields
Removed useless code, two GFK to one model don't work anyways…
Prepare 0.11
Revert "Removed useless code, two GFK to one model don't work anyways…"

This reverts commit 188182b97db6682ef0624404ba4ff0f74270dbdd.
Release 0.11.1
Updated travis.yml
Increased version to 0.12a1
Remove pointless import
Remove duplicate code
Proper (hopefully) fix for https://github.com/alex/django-taggit/commit/20a8063c4deb8fb3c5440787cd8114cb2fdf8537#commitcomment-4715554
Release version 0.11.2