Remove use of ZLL process in 7TeV configuration (and 8TeV btag) and repl...

...ace with ZL and ZJ

This pull request will update the setup files to use ZL and ZJ consistently instead of ZLL in the 7TeV vbf, and both 7 and 8TeV btag categories.  I'll circulate this request to the working group first to be sure everyone is happy with it, so perhaps best to wait on merging into the main branch. I've checked that the datacard creation step works ok with these changes, and that the max-likelihood fit runs as expected in the SM analysis.