Use a more lightweight library for slugs

[richardneililagan]

The current slug library (slug@0.9.1) seems to be too heavy and overarching for the purposes of this library --- it installs and builds unicode definitions. While that is all appreciated and probably sides with caution, using a more straightforward slug library (or maybe even just rolling out our own logic that performs the necessary algorithm) is much more practical.

[joshgoebel]

Suggestion of specific libraries?

[joshgoebel]

This is internal now.