Set up Auth0

[HannahBurgoyne]

• [x] set up crew users in Auth0 website
• [x] follow JWT auth challenge & rcmndr for assistance, tailored to our needs
• [x] test out login feature with a fake user
• [x] create component for handling new user data when registering, and redirect to this
• [ ] ensure user db is updated with new user data
• [x] write passing tests for server side
• [ ] write passing tests for client side