Feature/upgrade material ui

[mell0kat]

Description

• Upgrade material-ui. We were using an v4 alpha which was giving us some typescript issues
• Refactors the formatUpdatedAt function
• Refactors types in reducers to be more DRY

(Don't forget to run npm install next time you pull down master after this is merged)

Checklist

• [x] This PR contains tests (at least one (non-snapshot) test)