Display user email based on admin configuration
Description
User email is hidden across whole Zanata at the moment.
Require feature to allow admin to configure to display user email or not in Zanata.
API
project contributors list - when configuration for display user set to true
user service (private api for editor, /user/{username}) - when configuration for display user set to true
UI
user profile page - when logged in and configuration for display user set to true
