Fixing resource lookup under Wildfly

Old code always returns null when using WAR inside EAR. From spec: `Returns a directory-like listing of all the paths to resources within the web application whose longest sub-path matches the supplied path argument.`

That means return files under directory, not the files.
@garcia-jj, as I said it is not working on tomcat and jetty... after this change, when we try to start musicjungle we get a `javax.servlet.ServletException: A beans.xml isn't found. Check if is properly located at /WEB-INF/beans.xml or /WEB-INF/classes/META-INF/beans.xml`