User should be able to generate a notifier with e.g. rails g notifier UserNotifier new_notification

[yuki24]

User should be able to generate a new notifier with a command like below:

rails g notifier UserNotifier
rails g notifier UserNotifier new_friend_request
rails g notifier UserNotifier new_friend_request --only=apn

It should generate:

• app/notifiers/application_notifier.rb if missing
• app/notifiers/user_notifier.rb
• app/views/user_notifier/new_friend_request.json+apn.jbuilder (if action(s) is given)
• app/views/user_notifier/new_friend_request.json+fcm.jbuilder (unless --only=apn is given)

It should fail if config/initializers/fourseam.rb is missing.