Setup Flask login

[justinarat]

Can just follow the lecture to setup flask-login and this maybe.

This issue is dependent on issue #46 where login and signup forms were setup and issue #34 as it needs to add functions to the Users class.

TODO:

• [ ] Setup FlaskLogin
• [ ] Handle login and signup forms in account-creation endpoint
• [ ] TBA

[justinarat]

Decided to just setup FlaskLogin in pr #49 as other features depend on it and it needs to be done quick, so closing this issue.