Fixed sql_pgsql_table_exists() when used with a database containing multiple schemas.

git-svn-id: http://svn.code.sf.net/p/mrbs/code/mrbs/trunk@2801 25f7e783-145e-4f2d-a9f8-dd7182bfe9c7
Fixed upgrade.inc to work with multiple schemas

git-svn-id: http://svn.code.sf.net/p/mrbs/code/mrbs/trunk@2802 25f7e783-145e-4f2d-a9f8-dd7182bfe9c7