User model implementation

[trungams]

Following the discussion in issue #10. We will now try to extend our user model to support password authentication.

Feature/Enhancement Description

OAuth is being used for login so that new users don't have to register for a new account providing that they have a WCA account and ID. This puts a limit on who can sign in to our website, and some people might not need a WCA account in order to create meetup events.

Tasklists Suggestion

• [x] Extend our current User (Cuber) model to have a password field.
• [x] Implement registering.
• [x] Implement login with password.
• [x] Allow registered user to connect with their WCA account to sign up for events and competitions.
• [ ] Email verification. THIS IS IMPORTANT

Additional Comments

[trungams]

Got basically everything in 8b6e643ee466f9b06ffd50fee3087ef31aaf8d8f. We will see if they work with the event + registration tomorrow.