Fix path on Windows.

When running from an installed version of ParaView, all python files are
under <ROOT>/lib/paraview-#.#/site-package/. We need to add that location
to sys.path. Currently "import paraview" is failing on Windows binaries.

Change-Id: Ib332744e5c5e82f41ee1827fd7bca9ea10e92dd9
Merge topic 'fix_python_path_windows' into next

0ba800c Fix path on Windows.