gplazma2-xacml: revert version of opensaml

The privilege xacml client is incompatible with the newer opensaml library.
In particular, the client bootstrap method calls a method which is missing
in the newer version.

Restores opensaml to 2.4.1 (last compatible).  Also eliminates unused opensaml1 library.

Target: master
Request: 2.8
Patch: http://rb.dcache.org/r/6581/
Bug: http://rt.dcache.org/Ticket/Display.html?id=8244
Requires-book: no
Requires-notes: no
Acked-by: Paul