Fixed AssertionError for OPTIONS call on list-view that accepts PUT

[pmalmgren]

For issue #3356

An OPTIONS request on a @list_route decorated view with a PUT method raises an AssertionError, because the determine_actions method was trying to access get_object(). I added a check to this method to ensure that the view was not a @list_route decorated view before trying to check object permissions.

[xordoquy]

Closing this for reasons given in #3356