RFR: 8205119: SwingApplet demo should be removed

[Phil Race]

Bug: https://bugs.openjdk.java.net/browse/JDK-8205119
Webrev : http://cr.openjdk.java.net/~prr/8205119/
This demo only demonstrates how to create a Swing Applet, nothing more, but
Applet is now deprecated, and the demo can't be run without 
appletviewer, so remove it.

-phil.