Resolve "App is stuck in a redirect loop if user does not exist in laboite"

Closes #19 (closed)

To test :

• disconnect from Laboite and delete your user in database: meteor mongo -> db.users.remove({username:'xxxxxx'})
• open agenda and try to log in with keycloak (set laboiteURL in config.development.json)
• after logging in, a page should appear with instructions for creating account into Laboite
• after following instructions, you should be logged in Agenda after clicking on provided link