Added node rating stats to the ratings.get webscript (for each scheme):
average (mean) of all ratings for this node.
total (sum) of all ratings for this node.
count of all ratings for this node.
git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@21108 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261