refs https://github.com/TryGhost/Ghost/issues/5071
Upgrade messages are now shown on the About screen rather than as alerts. Notifications that are marked as `top` or `custom` are still shown as alerts to allow for certain upgrade messages to be given more visibility.
- remove old `upgrade-notification` service
- update the `upgrade-status` service:
- add a `message` property that contains an upgrade notification if any exists
- add a `handleUpgradeNotification` method that accepts a Notification model instance and extracts the `notification.message` property into a html safe string for use in templates
- when loading server notifications during app boot, pass notifications that aren't marked as `top` or `custom` to the new `handleUpgradeNotification` method
- update the `about.hbs` template to pull the upgrade message from the `upgradeStatus` service
no issue
- add eslint-plugin-ember, configure no-old-shims rule
- run `eslint --fix` on `app`, `lib`, `mirage`, and `tests` to move imports to the new module imports
- further cleanup of Ember globals usage
- remove event-dispatcher initializer now that `canDispatchToEventManager` is deprecated
no issue
- add ember-suave dependency
- upgrade grunt-jscs dependency
- add a new .jscsrc for the client's tests directory that extends from client's base .jscsrc
- separate client tests in Gruntfile jscs task so they pick up the test's .jscsrc
- standardize es6 usage across client