User module

One essential item in Dark is a User module. It should be trivial (take no more than 1 minute) to set up a user module. The user module should support:

• signing up, logging in and out
• password reset, including emailing
• password security - no visible passwords in a trace
• login with social accounts (where logins on multiple accounts can be combined)
  • github, twitter, facebook and google, at least
• a primary key that is not an email address
• easy integration with React and Vue, as well as iOS and Android
• Easy-to-use, styleable, HTML pages
• Profile images (pre-populated from gravatar)
• Tight integration with traces - see a users' profile image on the trace
• Tight integration with feature flags - easily enable a flag for sets of users
• Cookies
• JWT

And it should aim to, in the future, support:

• Multi-factor auth
• allowing this be a login system for backends written in other systems
• adding other social accounts
• ability to see an audit log of a single user
• ability to automatically delete a single user's data for compliance reasons
• levels of authorization

TODO: