Thread scopes through #matches?. #454.

Also add an apply_to_mentions attribute on Glitch::KeywordMute, which is
used to calculate scope.  Next up: additions to the test suite to
demonstrate how scoping works.

app/models/bookmark.rb

@@ -3,11 +3,11 @@
 #
 # Table name: bookmarks
 #
-#  id         :integer          not null, primary key
+#  id         :bigint(8)        not null, primary key
+#  account_id :bigint(8)        not null
+#  status_id  :bigint(8)        not null
 #  created_at :datetime         not null
 #  updated_at :datetime         not null
-#  account_id :integer          not null
-#  status_id  :integer          not null
 #
 
 class Bookmark < ApplicationRecord