Bug 12298: The "feed" MTT does not seem to be used and can be removed

Bug 12298: The "feed" MTT does not seem to be used and can be removed

The feed message transport type exists but nobody knows how it can be
used. This patch assumes nobody uses it and removes it.

Before removing the entry in the DB, the updatedb entry will check if no
foreign key exists in order to avoid a delete in cascade.

This path does *not* deletes the occurrences in the templates.

Test plan:
Apply this patch, execute the updatedb script and verify the
message_transport_types table does not contain the 'feed' entry if it was not
in use.

Signed-off-by: Nick Clemens <nick@quecheelibrary.org>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Patch will remove the confusing option to configure message texts for feeds.
Checked on a database with an existing feed type notice (not deleted) and
on one without any references to the feed message transport type (deleted!)

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>