Fixed regression introduced in r13755 that prevented the running of the...

Fixed regression introduced in r13755 that prevented the running of the GEOS/GDAL test suites without configuring Django settings; moved reference geometry data from Python module to compressed JSON fixture; put in workaround in tests for GDAL bug #3783.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14414 bcc190cf-cafb-0310-a4f2-bffc1f526a37