Fix for django 1.5

from django.views.generic.list_detail import object_list will not work
anymore
Optimize the query in `bulk_lookup_kwargs` for QuerySet args.

When passing a QuerySet to bulk_lookup_kwargs(), the queryset was
undesirably executed to get a list of IDs. This causes an unnecessary
performance loss.

There is no need to loop over a QuerySet to execute a IN (1, 3, 4) query.
Instead, just allow the ORM and database to execute a IN (SELECT id FROM ..) query.
In a real life app with a large set of objects, the difference in performance is noticeable.
Renaming README with proper Markdown extension
Updated AUTHORS.txt
Fixed setup.py
Fixed test runner for Django 1.4
Fixed failing test for non-deterministic list order
Updated AUTHORS.txt file
added related_name param to TaggableManager
Updated AUTHORS.txt file
Add m2m_reverse_field_name to TaggableManager
Updated admin.py

- added the slug to the list_display
- added search_fields
Fixed a bug

Fixed an exception error that happens when someone adds a tag in a
different case, when a tag already exists in another case. In other
words when someone submits a new tag that creates the same slug as an
existing tag.
Made it so the exception catching is more database agnostic
Fixing database exceptions

All Django database backends capture the adapter exceptions an re-raise
them as django.db.utils exceptions, so it's safe and agnostic to just
capture these.
Don't catch DatabaseError