The upgrade to 1.5 requires that the plpgsql language is available in
postgres, but sometimes (e.g. versions of postgres < 8.3), the
database owner doesn't have permission to create the language, and the
admin will have to do it manually.

During the attempt to issue the CREATE LANGUAGE command, an sql
exception can be thrown when the db user has insufficient privileges,
so a generic 'nonrecoverable error occured' message is displayed
instead of the useful message instructing the admin to create plpgsql.
Catching the sql exception fixes this problem.

Change-Id: I176bdd1eee2247426ceedc6f165156d33eefbb42
Signed-off-by: Richard Mansfield <richard.mansfield@catalyst.net.nz>