#4 Add a signal emitted when Aquila closed all modules

[Martin Peniak]

yarprun server can be prematurely closed, update the following function:

void MainWindow::aboutToQuit()
{
//let modules know that this application is quitting
emit quitting();

///yarp::os::Time::delay(2); ---> this should be changed for wait for signal

//terminate the process running yarprun server
yarprun->terminate();
yarprun->close();

}