Editing collection: error 500 if collection name is removed

Resolves issue: http://code.google.com/p/otwarchive/issues/detail?id=1841

Controller checks to make sure the collection has a name before it proceeds with processing the update method. If there is not a name, the user is given a meaningful error and sent back to the 'Edit' form.
Basically, this uses the value of the name in the database to find the collection, rather than any unsaved changes to the name.