Types not registered if the PostGIS extension is installed in the database schema other than "public"

[gkresic]

It seems both net.postgis.jdbc.DriverWrapper and net.postgis.jdbc.DriverWrapperAutoprobe are assuming PostGIS is installed in public schema or at least somewhere on the user's search_path. However, it is not uncommon to install PostGIS in its own schema (like gis) to prevent name clashes with other extensions in the same database.

This is loosely related to #50.