Remove unneeded indices, improve error handling in background workers, don't needlessly reload reblogged status, send Devise e-mails asynchronously

db/migrate/20161122163057_remove_unneeded_indexes.rb

@@ -0,0 +1,7 @@
+class RemoveUnneededIndexes < ActiveRecord::Migration[5.0]
+  def change
+    remove_index :notifications, name: "index_notifications_on_account_id"
+    remove_index :settings, name: "index_settings_on_target_type_and_target_id"
+    remove_index :statuses_tags, name: "index_statuses_tags_on_tag_id"
+  end
+end