Fix test vtk python scope gil ensurer
This add a pqPythonManager::IntializeInterpreter method and modify the TestVtkPythonScopeGilEnsurer so it actually test the initialization of the GIL.
Edited by Mathieu Westphal (Kitware)
This add a pqPythonManager::IntializeInterpreter method and modify the TestVtkPythonScopeGilEnsurer so it actually test the initialization of the GIL.