sphinxdoc fails to build on jessie.

Removal of the V1 source code means that the file is now in a
different path.

This binary was a simple wrapper to manage daemonisation
which systemd does for us.

Close 879397

drop_materialized_views is new support and needs to be
conditional on finding a recent version currently installed.
Add output to show what the maintainer script is doing.

Some migrations can alter fields which already have a
materialized view in the database. Existing code already
refreshes all materialized views, so ensure that views are
dropped ahead of the sync, retaining creation in the refresh.