[SHAPE] Add support to mkPlots.py and mkDatacards.py

[giorgiopizz]

Should add support to Latinos mkPlot.py and mkDatacards.py.
One should work with compiled versions of a configuration folder and parse from there:

• samples dict
• aliases dict
• nuisances dict
  and so on.
  One preliminary version can be found here: gist

[giorgiopizz]

Scripts were added in a3a8ebb

mkPlot works, mkDatacards should be checked

Also examples' plot.py should be updated to work with the mkPlot syntax