A few changes

- updated to NNLO ttbar x-section (245.8pb)
- trying to fix the JER issue: the data jets were smeared to 0, which shouldn't happen. also, if no generated jet was found, the jets were smeared to 0 in MC events as well. A little dirty fix should take care of this, but need to understand and correct it properly. Currently, the confusing bit is, with the JER systematic applied, we get more jets that pass the selection in data (WTF?)
- added the JER systematic in start_2012_analysis.sh script
- added a suffix for output files with JER systematic applied
- some formatting changes