Added APIs to allow broken links due to deletions & new/modified files in a
workflow to be detected via sync service (differencing). Not configured
as transactions yet, nor has much testing been done, but things are starting
to shape up. Now also detecting broken IMG tags (as well as A tags).
Also, the linkvalidation service now has its own file extension excluder bean.
Eventually the old APIs will go away, but I'm leaving them in there for
now to make life simple.
git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@5992 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261
