[#566] Fix ProjectAdmin.add_view() to match 1.5

ProjectAdmin.add_view() is overridden to add functionality to the admin
form. For this reason it's necessary to check that the "original" code
matches the version of django we're running on. This is now fixed for
Django 1.5.
[#566] Cleanup of rsr/admin.py

Remove unused imports and old commented out code.
[#566] Merge branch 'feature/django-upgrade' into feature/566_fix_add_view_for_1.5

Conflicts:
	akvo/rsr/admin.py

Checked ProjectAdmin.add_vew for compatibility with Django 1.6
[#566] Remove part of admin.py accidentally added from old code
[#566] Missed one bit and realized that partner_clean() is old code too
Merge pull request #606 from akvo/feature/566_fix_add_view_for_1.5

[#566] Fix ProjectAdmin.add_view() to match 1.5 and 1.6