Add migration module with helper methods

Some changes on xhtml files can be scripted, we should define java classes that perform the migration, or at least deliver meaningful information to the user when changes cannot be done automatically.

This should be done in Java classes so that it's easy to unit test, and so that it can be reused by thrid party code (like Studio).

Features include:

• migration of a group of files recursively, given a filesystem path or a stream
• generation of a report of changes, or validation warnings when changes cannot be done automatically.

Currently changes include:

• automatic
  • tag library namespace changes (richfaces, a4j, seam-excel)
  • tag library attribute changes (reRender vs render + space instead of comma to separate multiple ids, ajaxSingle vs execute, a4j;param instead of a4j:actionparam... list to be defined)
• not automatic
  • a4j:ajax and a4j:support changes (still valid, need to check the criteria when this stops working)
  • rich:suggestionBox migration
  • maybe file upload components migration
  • value holder usage with selectActionBean interactions
  • nxa4j library removal (use nxh lib + f:ajax tag)
  • c:set scope="page" does not exist in JSF2, use scope="view" or scope="request" instead (or do not set a scope)

+ list all default files with DM/DAM/SC installed to generate warnings about template overrides (and encourage users to remove these overrides or at least migrate them)