Remove Distributions.jl

[frapac]

It seems that we do not need to use this package

[trigaut]

We use the function Categorical multiple times in noises.jl.
Doesn't it belong to Distributions?

[leclere]

It does, maybe we do not need it. It is not prioritary.

[frapac]

We start implementing noise modeling elsewhere:

https://github.com/frapac/Scenarios.jl