Backport changes to run_test.pl script

This will help us with testing extension upgrades after
the changes introduced in the upgrade scripts

git-svn-id: http://svn.osgeo.org/postgis/branches/2.1@12596 b70326c6-7e19-0410-871a-916f4a2858ee
ST_AsRater changed signature, wasn't obsoleted

git-svn-id: http://svn.osgeo.org/postgis/branches/2.1@12597 b70326c6-7e19-0410-871a-916f4a2858ee
Handling of raster_columns table/view needs to be done _before_

Or we'd drop the view after...

git-svn-id: http://svn.osgeo.org/postgis/branches/2.1@12598 b70326c6-7e19-0410-871a-916f4a2858ee