Fix Gatsby to use Material-UI CSS properly, update/remove deps

[humphd]

Issue This PR Addresses

1. Fixes Remove second react dependency #728
2. Fixes Remove spam-filter module and associated code #415

Type of Change

• Bugfix: Change which fixes an issue
• New Feature: Change which adds functionality
• Documentation Update: Change which improves documentation
• UI: Change which improves UI

Description

This fixes master so that CSS styles from Material UI work in both build and develop modes. I've also fixed a few other things in an attempt to figure out what was wrong.

1. Changed the react version to be pinned to the one we're using in the frontend, removing second React dependency
2. Added eslint ignore for the new plugin I had to pull in to our tree to get CSS in MUI to work
3. Removed spam filter and sentiment analysis deps, code, and tests/test files.
4. Changed our frontend package.json to use pinned versions vs. package-lock.json
5. Fixed our gatsby config to properly deal with CSS from MUI
6. Added a theme.js file to get the MUI-Gatsby plugin to work--we'll probably need to fix this later.

NOTE: you should remove your node_modules/ folders and reinstall them

[manekenpix]

👍