Edited ForeignKey fields in models to avoid cascade on delete behavior. References to Collections will be set to null. Deleting Machines or Items with associated bags will raise an error. Refs #111
Added tests for new non-cascade-on-delete rules. Fixes #111
Added default now() timestamp for BagActions
Added fake ids to objects in NoCascadeTestcase to prevent calls to idservice in TravisCI. Fixes #111
Merge pull request #116 from gwu-libraries/block_cascades

Block cascades