cleanup obsolete options and parameters

Details:
- delete now-obsolete options and parameters (model, template,...)
- reduce vertical space
- update docstrings
remove empty lines, remove default parameters

Details:
these parameters are required. Without them we cannot run any fbu, and
we should just exit. We should specify default values only once, in
the top-level script, as cmd-line defaults.
update default values
simplify and clarify loop

Details:
prefer list comprehension where possible.
This also makes clear that we're adding a bkg contribution and a
migration contribution.
It also allows for an empty background (will be needed for the bump,
for example).
initial draft (spectrum similar to fbu preprint)
significant re-write

Details:
- factorize the code in well-defined functions
- add docstrings explaining what I am doing
- rewrite most of this script. Now plotting and using the resulting
histograms as bins/counts that can be used for the unfolding.
- compute normalized response matrix
- add plotting functions
utils to write/read np.array from/to json
separate the generation from the unfolding

Details:
two separate logic steps: generate the pseudo-data, and then unfold.
The pseudo-data can come either from the json file, or be generated.
almost there, but pyfbu does not work

Details:
complaining about template. I thought it wasn't needed anymore.
Need to ask clement and Francesco about it.
flip up-down the response matrix

Details:
the vertical axis of the histo provided by histogram2d is reversed
(see
http://docs.scipy.org/doc/numpy/reference/generated/numpy.histogram2d.html)
delete assignement of obsolete parameters
reduce the number of samplings to test things out faster
typo
regenerate when json is not there
try to adjust lower/upper
Merge branch 'example-bump' of github.com:gerbaudo/fbu into example-bump

Conflicts:
	python/generate_bump.py
	python/utils.py