RFR 8241749: Remove the Nashorn JavaScript Engine

[sundararajan.athijegannathan at oracle.com]

Please review.

Nashorn script engine modules (jdk.scripting.nashorn, 
jdk.scripting.nashorn.shell) and jjs tool are removed.

Bug: https://bugs.openjdk.java.net/browse/JDK-8241749

JEP: https://openjdk.java.net/jeps/372

CSR: https://bugs.openjdk.java.net/browse/JDK-8241751

Webrev: http://cr.openjdk.java.net/~sundar/8241749/webrev.00/index.html

Few tests that use nashorn are worked around by @ignore or deleting 
relevant nashorn test sections. Separate test bugs have been filed to 
handle these.

https://bugs.openjdk.java.net/browse/JDK-8242860

https://bugs.openjdk.java.net/browse/JDK-8242859

https://bugs.openjdk.java.net/browse/JDK-8242858

https://bugs.openjdk.java.net/browse/JDK-8241982

https://bugs.openjdk.java.net/browse/JDK-8235594

Thanks,

-Sundar