refs #6039
- add `jquery-deparam` ember testing dependency for use in mirage config
- setup necessary mirage fixtures & endpoints for successful testing of setup flow's happy-path
- add happy-path acceptance test for setup flow
refs #6039, closes#6047, closes#6048
- delete old/unused fixtures file
- add failing tests for #6047 & #6048
- redirect to sign-in if we get a 401 when making an API request
- fix incorrect `this.notifications` call in tag controller
- raise `authorizationFailed` action in application route's `sessionInvalidated` hook so that it can be handled by leaf routes (fixes re-auth modal display)
- close "saving failed" alert when successfully re-authenticated
- adds a "window-proxy" util so that we can override `window.*` operations in tests
- fix `gh-selectize` attempting to register event handlers when the component has already been destroyed
refs #6039
- adds ember-cli-mirage dependency
- sets up mirage to match our API endpoints and responses
- adds fixture data for settings that are always present for all blogs
- converts existing acceptance tests to use mirage
