in build, add path to test resources

matching the path we use in the NetLogo repo

useful for adding Tortoise-only language tests
add a place to put Tortoise-only language tests
get newer headless jar that has some additional death tests
Merge pull request #70 from NetLogo/newer-headless-jar

get newer headless jar that has some additional death tests
Merge remote-tracking branch 'origin/master' into nashorn
fix `nobody` handling on Nashorn
fix `remove-duplicates` prim on Nashorn

the old code assumed that when you iterate over the key-value pairs in
an object, the keys always come back in the insertion order. not
guaranteed by spec, and actually failed on Nashorn