Authenticate with Twitter Account

[mzrimsek]

Users should be able to sign up/login with their Facebook account.

• [x] Configure Firebase provider
• [x] Configure Twitter OAuth for dev environment
• [x] Configure Twitter OAuth for prod environment
• [x] Add Twitter login action, reducer case, and effect
• [x] Add Twitter login button in LoginComponent
• [x] Add Twitter sign up button in RegisterComponent

[mzrimsek]

Moving this back to "To Do" because it's pending developer account approval.