feature: generalize from reliance on bash

[nick1udwig]

Is your feature request related to a problem? Please describe.
Parts of kit don't work for non-bash users (e.g. zsh) because we reference, e.g. ~/.bashrc

Describe the solution you'd like
At a minimum we need to have clear error messaging around failures due to non-bash shells.

Ideally we would handle other shells gracefully and be generalized wrt shells.