UserManagement: fixed devise to work with new fields of User model
 - overrode devise sanitizer in application.rb
 - created custom sanitizer in user_sanitizer.rb
 - initialised custom sanitizer in initializers/sanitizers.rb

 Followed guide: http://blog.12spokes.com/web-design-development/adding-custom-fields-to-your-devise-user-model-in-rails-4/