[8u] approval request for 8135054:Add more samples to nashorn samples directory

[Sundararajan Athijegannathan]

Please approve.

Bug: https://bugs.openjdk.java.net/browse/JDK-8135054
jdk9 review thread: 
http://mail.openjdk.java.net/pipermail/nashorn-dev/2015-September/005152.html
jdk8u webrev: http://cr.openjdk.java.net/~sundar/8135054/8u/webrev.00/

Backporting all samples "as is" except for two jdk9 specific samples - 
jrtlist.js (requires jrt file system), java_completion.js (requires jshell).
CC'ing nashorn-dev.

Thanks,
-Sundar