common code down into the base class.
Added configuration value to control if unknown users should be mapped to the guest account.
Fixed a couple of uncaught access denied exceptions in the CIFS protocol handler.
git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@2317 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261
cc503b2ac8