ProjectExplorer: Fix Project::displayName changes

The only project manager that actually sometimes changes the displayname
is the cmake project manager. And that one failed to emit the right
signal. And since the signal was never emitted a few places handled the
signal wrongly.

Change-Id: I4aa75dc3032efe49263143dbadb7585a378b9be9
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/cmakeprojectmanager/cmakeproject.cpp

@@ -383,6 +383,7 @@ bool CMakeProject::parseCMakeLists()
 
     }
 
+    emit displayNameChanged();
     emit buildTargetsChanged();
     emit fileListChanged();