Improvements to makefiles

- Added cmake file to find D-Bus
- Removed remaining AddEngine stuff
- Fixed cross compiling for windows trying to use dbus after previous commit
- Compilation tested on Linux, FreeBSD, OpenBSD and cross compilation from linux for windows using mingw compiler

src/engine/phononengine.cpp

@@ -23,7 +23,7 @@
 #include "phononengine.h"
 
 #include "core/logging.h"
-#include "taskmanager.h"
+#include "core/taskmanager.h"
 
 PhononEngine::PhononEngine(TaskManager *task_manager)
   : media_object_(new Phonon::MediaObject(this)),