Change ownership when copying an exercise in assignment builder

[bnmnetp]

When a user makes a copy of an exercise my guess is that the desired workflow is as follows:

1. search for an exercise
2. click the copy button to make a new copy
3. edit the question

Right now this workflow is hard (or impossible) to achieve for a couple reasons

1. When making a copy the person making the copy should become the owner.
2. You don't get the opportunity to edit the question until you have added it to the assignment.

At a minimum I think we should change the logic so that when you copy the owner and basecourse are update to the current user and the basecourse of the book they are currently working in.

I think it would be much more convenient to to have the edit button (or at least some explanation) that says you have to first add the question to your assignment and then edit it.