Added rumba

Marlin/Configuration.h

 // 7  = Ultimaker
 // 71 = Ultimaker (Older electronics. Pre 1.5.4. This is rare)
 // 8  = Teensylu
+// 80 = Rumba
 // 81 = Printrboard (AT90USB1286)
 // 82 = Brainwave (AT90USB646)
 // 9  = Gen3+