Plugin for Authentication

If the plugin is enabled and user tries to log in:

• Plugin tries to authenticate the user with its own database
• If there is no such a user, Poulpe is asked for it.
  • If Poulpe answers with "Yes, there is one", then we save the user in internal JC database*
  • If Poulpe answers with "I don't know him", then user should be shown with authentication error
• If user exists, but the password is wrong, Poulpe is asked to authenticate the user via REST
  • If Poulpe answers successfully, then users's password in JC internal database should be updated
  • If Poulpe answer is negative, then user should be shown with authentication error
• If Poulpe does not respond and it was not possible to authenticate user against JC internal DB, an error "Authentication failed. Authentication service is not available, that might be the reason you cannot login. Please contact administrator or try later" should be shown.

* Note, that right now we don't have 'an internal JC database' - the DB is shared between apps, but in the future JC will have a separate DB from Poulpe.