Add optional real name and icon to accounts

[justinanderson]

• [ ] Add an optional first and last name field to account registration form.
• [ ] Add an optional first and last name field to the social auth registration form, prepopulated with users real name from their social identity provider if they allowed it.
• [ ] Show that real name on the account settings page.
• [ ] Show that real name in the /api/v1/user response.
• [ ] Do the same for an optional profile icon from their social identity provider, gravatar, or a file upload.
• [ ] Add layer to translate DataHub username to database username