Adding some plots and refactor

- I have rename regression to doregression(similar to kmeans)
- I added some functions for ploting graphics
- Refactor base on pep8
- Marta, i added  df = self.df.copy(deep=True) because otherwise you were passing self.df as a reference and is not what you wanted, no?
- Sorry, I have notices now that I have overwritte again the path of the files but well... we should rewrite this to pass as args but not time for now.