title: Start app by hardwarekey Android Application
body: <p>I just started creating apps, and now I want to know how to build something that 
  helps me to start an app, by execercising a volume down/up press during the sleepmode of my phone. 
  I think that it will need an OnReceive Method or something that works like a onclicklistener but i cant figure it out. </p>
  
  <p>Greetings</p>