(Android) Fix for crash when there's no connected devices.

lib/devices/android/adb.js

@@ -420,7 +420,7 @@ ADB.prototype.getDevicesWithRetry = function(timeoutMs, cb) {
       } else {
         cb(null, devices);
       }
-    });
+    }.bind(this));
   }.bind(this);
   getDevices();
 };