Add category to data-tribejson and create category class tag

This works fine if there is only a single category per event. If there are more then it's likely that only the last category slug will have a class tag created. Definitely needs to have class tags created for all categories but I don't know how to pass an array via the json or pull the data out of the json array in the mobile view.

BTW, ECP week mobile view will need similar changes.

Sorry for the extra stuff. Not sure how to remove it.