Feature Implementation of issue [#67](https://github.com/jeemok/better-npm-audit/issues/67)

[bencivjan]

I and @dchahuan have implemented the specification of dev dependencies and production dependencies in the audit. This was requested in issue #67.

We completed this by always running a npm production audit and taking the difference in results from the requested user audit. If results from the requested audit do not exist in the production audit, we know they are dev dependencies and can mark them as such in another column.

This gives developers more information about which dependencies they need to focus on fixing.

We modified the tests that create mockups so that they accurately the new table.

Please let us know if there are any questions, concerns, or requested additions/changes.