Tree checkbo node impl

git-svn-id: http://primefaces.googlecode.com/svn/primefaces/trunk@9416 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c
Bug fix

git-svn-id: http://primefaces.googlecode.com/svn/primefaces/trunk@9417 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c