Review changes made for Issue #53 CMake

I've made all the CMakeList files the project needs. I managed to get the project to build, compile and install. However, when I try to run the qmlscene ui/main.qml, it can't seem to find the directories where the plugins are installed. Could you have a look?
This seems to build correctly, but I get errors on my system when running, but I think it's a local problem for me. Otherwise, changes are good. Added Bool value as well, but the NOT statement only appears now in the main CMakeLists.txt file.