RFR 8167018: Nashorn and jjs should support --module-path and --add-modules options

[Sundararajan Athijegannathan]

Please review.

Bug: https://bugs.openjdk.java.net/browse/JDK-8167018
Nashorn webrev: 
http://cr.openjdk.java.net/~sundar/8167018/nashorn/webrev.00/
JDK webrev (jjs tests): 
http://cr.openjdk.java.net/~sundar/8167018/jdk/webrev.00/

Thanks,
-Sundar