[Building Sakai] CAS and other filter configuration for login tool

[John Bush]

I did some work yesterday that I'm not sure anyone else cares about.
But if someone is interested let me know and I'll submit a jira/patch.

We had a long standing issue of configuring CAS/Shib and other signon
mechanisms that require servlet filters.  The issue is that you have
to modify web.xml's to configure these things.  That mucks up our
whole binary deployment model, and leads to a bunch of annoying
practices for managing those changes.

So what I did was create a way to drop a spring config file in
sakai.home that wires up your filters with their configuration.  I
built on Spring's DelegatingFilterProxy and ContextLoader to do this
in a way that works if you have this file in your sakai.home folder or
not.

Like I said if this has value to anyone else let me know.
--
John Bush
602-490-0470