Require user registration to submit a talk proposal

[jrrickerson]

Unfortunately, public web applications attract a lot of spammers, bots, etc, and simple typos in email addresses can sometimes make speakers for proposed talks impossible to reach. Add a user registration system and require a user to be logged in to submit a talk proposal.

• Add a registration system that validates a user's email address.
• User authentication via third party (Facebook, Google, etc) is ok too as long as an email address can be acquired for the user.
• Ensure new users are NOT granted access to the admin.
• Create a new Speaker model (to avoid a direct link to the User model from Talk). Give the Speaker model a 1 to 1 relationship with the User model. Get the model dynamically to account for custom User models: https://docs.djangoproject.com/en/1.11/topics/auth/customizing/#referencing-the-user-model
• Change the Talk model to link to the Speaker model for speaker information, rather than using free-text fields.
• Show speaker information (name, email address) on the Talk admin as read-only fields

[jacques-cadet]

Add registration

• User authentication and permissions.