(minor) Make ORMTable handle failed queries nicely.

Database::select will return false if a query fails and the DB object
is set to "ignore errors" mode. ORMTable now detect this and throw
a DBQueryError, overriding the ignore errors mode.

This change also adds a dummy implementation for ORMTable to ORMTableTest,
so tests can be run on the base implementation.

Change-Id: I5d87295626c0800c38f807d19becb312ba7cc956
Merge "(minor) Make ORMTable handle failed queries nicely."