#63 Ensure that entries are written to watchdog table

solves https://github.com/backdrop/backdrop-issues/issues/63
I don't see how the `dedicated_watchdog_connection` would be set up beforehand. The only place the connection is currently registered is in the dblog.test file, so this *only* exists during test runs, not during the normal execution of a page. Shouldn't this database connection be registered somehow either earlier (before the error happens) or on-the-fly when it needs to log an error?