Add a test to demonstrate #92
Use `admin_urls` for action links in admin history list
Fix 'other_admin' test
Removed `history_user` link from change admin page
Test specific change admin page as well
Use `render` instead of `render_to_response`
Document description of `revert_url`
Document changes
Revert "Removed `history_user` link from change admin page"

This reverts commit d5c7985863b17b3a70a986771ab4dfce5d2d450e.
Handle displaying changes in an admin site with no user model view
Merge pull request #111 from treyhunner/allow-non-default-admin

Allow non-default admin instances
Update models.py

When using the request middleware, if the user is anonymous an error is raised stating that the 'history_user' attribute must be an instance of User. As this field can be null, get_history_user has been updated to return None if the user is not authenticated. Also made the returning of None explicit.
Update test_admin.py

Added test for allowing Anonymous user when using HistoryRequestMiddleware.
Update test_admin.py
Update test_admin.py
Added cleaning up thread local to tearDown()
Fix Django 1.7 version pinning for tests