Include Boston and Lawrence data in MA analysis

[mikemahoney218]

As it stands, our MA dataset does not include information on Boston or Lawrence. Issues #14 and #15 reflect two different approaches to rectifying this challenge. Should both or either be completed, we would want to then combine the NIBRS dataset with the data for those cities and rerun our MA analysis.

This may already be completed; I'm migrating issues from the Wiki to GH Issues now.