Added PermissionGroup Enum to replace usage of raw strings in @group_required with approriate enum.
Fixes Issue#227
Fixing bug that cause Build Error.
More Fixes.
fixing build_id file path now that BASE_DIR is properly set to the root vcweb directory
fixing deploy confirm message
adding ExperimentMetadata.active field for additional filtering in experimenter dashboard

--HG--
extra : amend_source : 4604ccd806e62b218e3c888eaf85e932f3171c80
minor refactoring, removing PERMISSION_GROUPS
tweaking UI a bit, removing edit/delete configurations
fixing tests
removing groups on experiment restart and always adding new users to the Participants group when registering
participants.

getting rid of perms check on update_experiment, revisit again later
simplifying interface, removing unused / dangerous actions
Adding code to mark required fields in forms. Fixes Issue #233
adding more Experiment tests, fixing an exposed bug in elapsed time comparisons