WFLY-1373 Fix dependency on sun.jdk to allow Javascript engine to be found

Related JIRA https://issues.jboss.org/browse/WFLY-1373

The commit here fixes the dependency on sun.jdk to "importServices" and allow the Javascript engine to be found. The commit also enables a @Ignored test to conditionally run against specific JREs so as to have this test enabled against Oracle JRE and disabled against OpenJDK JRE.