Customizable dragmodes for tree

git-svn-id: http://primefaces.googlecode.com/svn/primefaces/trunk@9289 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c
Removed duplicate

git-svn-id: http://primefaces.googlecode.com/svn/primefaces/trunk@9290 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c
Do not update selections if drop target is not draggable

git-svn-id: http://primefaces.googlecode.com/svn/primefaces/trunk@9291 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c