This provides a way to set the level of involvement that a user has with
a collection, and from which we determine the level of notifications to
send. Users can be access-only, watching, or being notified about
everything.
If you're access-only, you won't get an notifications. If you're
watching, you'll only get notifications for the items you're watching
(which includes the items you've been assigned, have commented on, etc).
If you're set to everything you'll get notifications about all activity
in that collection.
This change replaces our previous concept of subscriptions. Where
previously you'd subscribe to a collection to get notifications in it,
now you'll simply set the notification level on your access.
The previous implementation would delete all accesses if the bucket
was not all_access.
I think it's simpler to move the bucket workflow into a separate
Buckets::WorkflowsController, rather than deal with different sets of
params from different forms in the existing BucketsController.
Kevin McConnell