Ebuild for mate-applet-lockkeys

Panel applet that shows which of the CapsLock, NumLock and ScrollLock keys are on and which are off.
Useful on laptop keyboards without LEDs
![applet-lockkeys](https://cloud.githubusercontent.com/assets/1297574/4103142/46f689e4-314c-11e4-9102-364546b4bdd7.png)