Whitelist for a minimal IGT-US-BUild

Added a whitelist which enables all packages to build only the MITKCore
and the Modules needed for IGT und US. No GUI no Plugins. Also modified
the CMake in the Utilites directory because the qtsingleapplication was
always build even if use QT was disabled and this caused a build error.
Now qtsingleapplication will only be built if qt is enabled.