First step in enabling UV-CDAT testing data.

For now we just enable getting the testing data and
make the location of it a CMake variable. For ParaView,
I'm setting the value as well to be used there.
Making the cmake variables more consistent.
Merge remote-tracking branch 'devel/130_download_test_files'

* devel/130_download_test_files:
  Making the cmake variables more consistent.
  First step in enabling UV-CDAT testing data.