RFR of JDK-8159785: Add test that tests ClassLoader.getResource/getResources in Multi-Release Jar

[Hamlin Li]

Would you please review the following patch?

bug: https://bugs.openjdk.java.net/browse/JDK-8159785
webrev: http://cr.openjdk.java.net/~mli/8159785/webrev.00/

JDK-8151542 <https://bugs.openjdk.java.net/browse/JDK-8151542>fixed bugs 
and added test to verify Class.getResource works as expected, but there 
is not test to verify that ClassLoader.getResource/getResources works 
well too.

Thank you
-Hamlin