Merge pull request #473 from Salandora/EmergencyBug

Emergency Stop should not only trigger an event but also at least cancel the print

Closes #448

src/octoprint/util/comm.py

@@ -1206,6 +1206,11 @@ class MachineCom(object):
 
 		return None
 
+	def _gcode_M112(self, cmd): # It's an emergency what todo? Canceling the print should be the minimum
+		self.cancelPrint()
+		return cmd
+
+
 ### MachineCom callback ################################################################################################
 
 class MachineComPrintCallback(object):