Allow filter links to be used in combination

Means you can see, for example emails that have failed.

Means adding:
- logic to generate links which can have a type parameter, a status
  parameter, or both
- a ‘pill’ UI component for seeing which filters you currently have
  applied
- some logic to change the page title based on which filters you have
  applied

app/assets/stylesheets/main.scss

@@ -48,6 +48,7 @@ $path: '/static/images/';
 @import 'components/email-message';
 @import 'components/api-key';
 @import 'components/vendor/previous-next-navigation';
+@import 'components/pill';
 
 @import 'views/job';
 @import 'views/edit-template';