Merge from 5.1.3

git-svn-id: https://primefaces.googlecode.com/svn/primefaces/trunk@12024 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c
Fixed #7627

git-svn-id: https://primefaces.googlecode.com/svn/primefaces/trunk@12025 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c
bugfix 

git-svn-id: https://primefaces.googlecode.com/svn/primefaces/trunk@12026 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c
Keyboard support for Tree

git-svn-id: https://primefaces.googlecode.com/svn/primefaces/trunk@12027 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c
refactor

git-svn-id: https://primefaces.googlecode.com/svn/primefaces/trunk@12029 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c