Vbf tag

Hi Seth, 

As discussed, this pull request contains:

* VBFTagProducer.cc and associated files to tag VBF events (2 MVA classes, VBFTag class, MVA producer files and VBFTag categorisation, with matching python modules etc).
* New globeLikeTreeMakerWithTags.cc, which makes the same tree as globeLikeTreeMaker.cc (which is now basically redundant) but the MVAs have been removed (since they now have their own classes and producers) and the Tag info has been pulled in from the above. Note that since the MVAs have been moved, the MVA info which goes into the tree comes from the Tag info... 
*PU rejection on dijet candidate jets now implemented in VBFMVA tag.
* Tree also has two new variables: flash_Untagged_Category and flash_VBTag_Category which return the integer value of the categories int he respective tags (and -1 otherwise) for validation of Tagging framework.
* New flashgg_tree_maker_tags.py python config to run the tree maker with tags.
* Dijet info for VBF events available via the VBFTag class.

Things still to do (eventually):
*validate tag assignments.
*validate VBF dijet jet properties
*move MVA weight files to their appropriate  location (eg TagProducers/data ?). & obviously retain MVAs
*figure out best threshold for PU veto on candidate VBF jets (currently ~0.7 if i recall)
*rename variables and methods consistently (eg inconsistent use of mva, Mva, MVA...)
*make sure no unnecessary info if being loaded into the producers (eg, I'm pretty sure I no longer need to load the VBFMVA info into VBFTagProcucer.cc)

But as you say, let's synchronise and then decide next steps...

Louie