Modify and add some test fixtures.
Add unittests for can_view. Incomplete.
Make read_source return both editable and viewable.

Now read_source takes a bool that tells it whether to get editable
objects for a user or just viewable/assignable objects.
Add can_view to model managers.
Code refactor.
Refactor some unittests.
Add method can_edit to managers.
Make crud views work with can_view.
Make adding new objects check can_edit first in ajax.
Fix code error in Device can_view.
Merge branch 'development' into jdev