Added a new flag called PARAVIEW_QT_VERSION that can be set to either 4 or 5.
Depending on the value of this flag, the appropriate Qt version is looked for
and built against.

If PARAVIEW_QT_VERSION==5, the necessary Qt5 modules can be
imported by including the script "ParaViewQt5.cmake". This script also sets
important Qt variables used throughout the project.

Setting the officially supported version of Qt5 to 5.0.2. Although, paraview
compiles fine against Qt-5.0.0, there are known issues that prevent it from
being fully functional (https://bugreports.qt-project.org/browse/QTBUG-28872).
Setting the minimum Qt5 version to 5.0.0.

Change-Id: I152529ef3da9492a44094c1e08444398a022d047