Modifications to signal model machinery.

- Fix for global scales fudge factors
- Tweaks to datacard creator
- Set MH to const when reading an already existing model
- Option to disable syst plots
Merge pull request #413 from musella/topic_datacard_and_plots

Modifications to signal model machinery.
Tweaks for combineHarveste.py
Signal model fixes:
- transfer matrix naming for correlated nuisances
- vertex deltafrac name

combineHarvester:
- automatic nuisance freeze / float
- fix parallel jobs working dir for --runLocal --parallel
Added signal model diagnostics/debug scripts
Merge pull request #415 from musella/topic_datacard_and_plots

Signal model and combineHarverster improvements/fixes
Partial correlation matrix implemented in signal model
Merge pull request #417 from musella/topic_datacard_and_plots

Partial correlation matrix implemented in signal model