JERSEY-2623 Package scanning not compatible with current JBoss EAP and WildFly

Hello, 

I am the technical project lead for the JBoss EAP and WildFly projects, and I am hoping you will consider this change which will address a major roadblock that our users are running into with deploying Jersey applications:

https://java.net/jira/browse/JERSEY-2623

This pull request provides a new VFS scanning implementation that is compatible with VFS2  (JBoss EAP5, EAP6) and VFS3 (AS6, AS7, WildFly 8, WildFly 9). It uses reflection to support the different ABIs as well as to avoid the additional VFS dependencies on the Jersey project (otherwise you would need a compile time/ provided dep on both 2 and 3, and with duplication).

Thanks!