Made initial changes to suppor editing and deleting categories.
Merge branch 'add_by_category' of https://github.com/cs3733-team4/wpi-suite into add_by_category
Committing to merge with Alex and finish deleting
Merge branch 'add_by_category' of https://github.com/cs3733-team4/wpi-suite into add_by_category
Further improved back end of deleting and editing category. WIP.

Alex: Check that categories are deleted from database upon Janeway
closing