Feature/expand jest config

[michaeljaltamirano]

This PR expands our jest.config.js file.

1. It removes the jest-config import because we're only relying on it to ignore node_modules. It's clearer to include that explicitly.
2. It adds coverage thresholds to our components (that currently pass) so we can maintain sufficient code coverages on the components, and enforce it.

The intent of this (and #130) is to make greater use of the tools we're using offer. In particular the coverage thresholds will help us stay sharp when we make changes and/or add components to the library, to ensure that we're including sufficient testing for those changes.

[daigof]

Im not very good at this config/devops things, but if it works it works.
Im curious what happen if we dont meet the coverage threshold???

[michaeljaltamirano]

Im not very good at this config/devops things, but if it works it works.
Im curious what happen if we dont meet the coverage threshold???

@daigof What should happen, with the pre-push in #130, is that the commits will not push until the threshold is met again. Here's what it looks like in the terminal:

(I raised the thresholds to 99% to induce the errors but the set thresholds in this PR are just below our current coverage, so it is just about maintaining our current coverage instead of adding additional work.)

[snags88]

This is a great addition. We should add this to Gatsby since we already have snapshot tests for most of our components there.

I already see that we have this in our demos & discussions board. We should definitely consider adding this to PocketDerm as well