Issue #22

A common interface for all types of distributions to return a distribution with the MLE parameters set that can be inspected per distribution after. It's a bit different than scipy, but they parameterize their continuous distributions from common parameters (location-scale family). Matlab `mle` function takes a data-set and distribution and returns an array of parameters, which is similar. 

For now, I excluded distributions that do not have a closed-form solution (gamma for example).