Issue 6736:	Tab - NPE if title is missing

git-svn-id: http://primefaces.googlecode.com/svn/primefaces/trunk@10954 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c
#6735 - refactored

git-svn-id: http://primefaces.googlecode.com/svn/primefaces/trunk@10955 5a70e874-a5cb-11dd-8af2-493fb0bb9f7c