Add notebook demonstrating CES on Cloudy

[bielim]

This jupyter notebook runs the full CES pipeline using Cloudy in a perfect model setting. May be helpful for users who want to see a CES application that runs in 5 minutes on a laptop. Requires installing Cloudy. Also note that the code is based on the assumption that Cloudy's "Distributions' module has been renamed to "PDistributions" (particle distributions), in order to avoid conflicts with Julia's Distributions.jl. The renaming hasn't been done yet, but it will be done soon.
Finally: There is definitely room for improvement in this code - e.g., FreeParams should be able to deal with the ugly forward and backward transformations (log/exp transform and z scores) of the parameters in a more elegant way.