add regression test image for mac dashboards

Need a second image for mac because vistrails won't produce the exact
same sized image as on linux for some reason.
Mac bug in cairo makes this image wrong but necessary - in interactive
use the actual image looks right.
Merge remote-tracking branch 'devel/add_mac_regression_test'

* devel/add_mac_regression_test:
  add regression test image for mac dashboards
Set INCLUDE_PYTHONHOME_PATHS to OFF for UV-CDAT ParaView build
Got UV-CDAT to start saying UV-CDAT instead of Python under Mac
Do not download source at the root level

It confused the make target
Updated location of pixman download source location
Merge remote-tracking branch 'devel/uvcdat_but_112_update_paraview_external'

* devel/uvcdat_but_112_update_paraview_external:
  Set INCLUDE_PYTHONHOME_PATHS to OFF for UV-CDAT ParaView build
  add regression test image for mac dashboards
Merge remote-tracking branch 'devel/uvcdat_fix_source_locations'

* devel/uvcdat_fix_source_locations:
  Updated location of pixman download source location
  Do not download source at the root level
Merge remote-tracking branch 'devel/MacName'

* devel/MacName:
  Got UV-CDAT to start saying UV-CDAT instead of Python under Mac
Merge remote-tracking branch 'remotes/devel/allow_system_mpi'

* remotes/devel/allow_system_mpi:
  Allow use of system MPI.