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
Merge branch 'master' into 5.1.x
Tagged 5.1.3-UR
Next maintenance iteration for 5.1.x