* Fix admin being able to suspend their own instance account
* Add text about the instance's own actor in admin view
* Change instance actor notice from flash message to template
* Do not list local instance actor in account moderation list
* Improve overview of accounts in admin UI
- Display suspended status, role, last activity and IP prominently
- Default to showing local accounts
- Default to not showing suspended accounts
* Remove unused strings
* Fix tests
* Allow filtering accounts by IP mask
* Dont use raise_error by itself (avoids warning)
* Add coverage for AccountFilter
* Improve coverage and refactor for Subscription#lease_seconds
* Improve coverage and refactor for NotificationMailer
* Simplify assignment of min/max threshold on subscription
* Remove unused account_params method in admin/accounts controller
* Introduce AccountFilter to find accounts
* Use AccountFilter in admin/accounts controller
* Use more restful routes admin silence and suspension area
* Add admin/silences and admin/suspensions controllers
