MOD - create collection_id field for each assignment

[Z4P0]

Ex:
[assuming nothing has been created, everything is fresh]
We create a collection --> collection_id = 1
we create an assignment --> assignment_id = 1, collection_id = 2

When we view the Assignment Overview we have the assignment_id in the URL hash.
That does not correspond directly to the correct Collection

If we can get the collection_id associated with an assignment returned that would fix the issue

[thequbit]

When would you like me to add this? It's going to take a rebuild of the database (which is fine), but it means we will loose everything that is currently in there (again, which is fine).

I'm going to implement it on my fork, and we can merge when you're ready.

[thequbit]

Looks like I should be doing this right away.