New Backbone versions no longer automatically set this on the object,
you have to pass it to initialize().

Allows user modifications to persist.

Provides automatic pre/post snapshots for each yum transaction,
just like the official plugin for zypper (SUSE systems).

Related: rockstor#1432

Embeds a Backform form within our standard Bootstrap panel element.
Can be used just like a Backform.Form view, because all constructor
arguments are passed on to the form.

Looks a little cleaner and more appropriate to me.

This reverts commit 4eca949.

Newer versions of Backbone no longer implicitly attach these
to the view, so the relevant initialize functions now do so
explicitly.

Allow retrieving individual snapshots as well as full list.

This allows the collections of snapshots to be nested below their
configuration name in the web API.

This is better suited to snapper than the ListCreateAPIView, since
snapper's interface does not return Django models or querysets.

Configured subvolume is already returned by snapper. Return snapshot
userdata as a dict because that's what SetSnapshot accepts.

Necessary to make deletions function appropriately.

It was not responding to model deletion events.