LP#1684202: Protect against missing features; Make feature more general

LP#1684202: Protect against missing features; Make feature more general

I've wrapped the BroadcastChannel code in a test derived from the auth version
of the same concept.  Also broadcasting the full set of record IDs and the
pre-update call number IDs for other interfaces that might be interested. The
channel name is also made more generic and made to follow the precedent from
the auth channel name.

Signed-off-by: Mike Rylander <mrylander@gmail.com>
Signed-off-by: Chris Sharp <csharp@georgialibraries.org>