RFR 8076646: nashorn tests should avoid using package names used by nashorn sources

[A. Sundararajan]

Please review http://cr.openjdk.java.net/~sundar/8076646/ for 
https://bugs.openjdk.java.net/browse/JDK-8076646

Although webrev looks somewhat big, the changes are mainly renaming 
packages, directories, resources, script paths.


-Sundar