Added tests for PostGIS geography support; added `proj_version_tuple` to...

Added tests for PostGIS geography support; added `proj_version_tuple` to PostGIS spatial backend operations; made `distapp` tests take into account different datums in PROJ.4 4.7; and added svn:ignore properties for recently-added directories. 


git-svn-id: http://code.djangoproject.com/svn/django/trunk@11971 bcc190cf-cafb-0310-a4f2-bffc1f526a37