Merge pull request #325 from shenrie/master

Enhance unit test for prepare update framework
Merge pull request #326 from shenrie/master

Added ability to return optional error messaage from XACML rule
Merge pull request #327 from shenrie/master

Minor fixes for policy decision point
Fixed agent get parameters logic to exclude aparam_get functions
Many minor changes to policy framework to help with performance and muti-threading