prep for release of rc2 (I know but too many new tickets closed in rc1 cycle and want to wait for geos)

git-svn-id: http://svn.osgeo.org/postgis/branches/2.1@11725 b70326c6-7e19-0410-871a-916f4a2858ee
flip branch to rc3 (hopefully we won't need it and can go straight to release)

git-svn-id: http://svn.osgeo.org/postgis/branches/2.1@11727 b70326c6-7e19-0410-871a-916f4a2858ee