Add "locked" flag to accounts, prevent blocked users from following, force-unfollow blocked users

db/migrate/20161222201034_add_locked_to_accounts.rb

@@ -0,0 +1,5 @@
+class AddLockedToAccounts < ActiveRecord::Migration[5.0]
+  def change
+    add_column :accounts, :locked, :boolean, null: false, default: false
+  end
+end