Fixed #176 -- Disallow multiple TaggableManagers with the same through model.
prefetch_query_set was also renamed to prefetch_queryset
reverse to make the current standard of 'queryset' the default
Exclude tests/ from install
Added tox file.
Merge pull request #181 from rizumu/get-prefetch-queryset

Get prefetch queryset
Typo.
Update api.txt

Minor fix, 'slugs' is a method bound to TaggableManager
Merge pull request #194 from krmboya/patch-1

Update api.txt
Add ``is_featured`` field to the ``Tag`` model.

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