Update managers.py

Fixes for Django 1.6 (as of beta 1)

Signed-off-by: Sævar Öfjörð Magnússon <saevar@overcast.io>
Update managers.py

Editing comments.

Signed-off-by: Sævar Öfjörð Magnússon <saevar@overcast.io>
Update managers.py

fixed bad indent.

Signed-off-by: Sævar Öfjörð Magnússon <saevar@overcast.io>
Updating text to reflect macaddr regex tests for Django 1.6

macaddr searches were broken pre 1.6.  Updated test to reflect the correct way to regex search on a macaddr.

Signed-off-by: Sævar Öfjörð Magnússon <saevar@overcast.io>