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 AS5, EAP5) and VFS3 (EAP6, 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).

Since I work for Red Hat, I believe we already have an OCA between our companies (since we contribute on other EE and SE projects), but let me know if I do need any additional steps. 

Thanks!