DBSCAN algorithm (#1207)

* Added dbscan in two formats. A jupyter notebook file for the
storytelling and a .py file for people that just want to look at the
code. The code in both is essentially the same. With a few things
different in the .py file for plotting the clusters.

* fixed LGTM problems

* Some requested changes implemented.
Still need to do docstring

* implememted all changes as requested

Author: cozek