#2441 Tiger geocoder uses new features only available in Postgres 9.3.  Changed to not use CREATE .. IF NOT EXISTS and use DO instead.  Also revised extension to upgrade loader (it wasn't before)

git-svn-id: http://svn.osgeo.org/postgis/branches/2.1@11851 b70326c6-7e19-0410-871a-916f4a2858ee