title: Rails Migrations - Alternative name for a foreign key?
body: <p>In my application I have 3 tables, users, lists, tasks.</p>
  
  <p>Users and lists is a many-to-many relationship, tasks belong to lists, and users can complete tasks.</p>
  
  <p>For my migration, when a user completes a list I'd like to store who it was completed by in the database but I'm unsure how to do this.</p>
  
  <p>I could simply add <code>t.integer :user_id</code> to my tasks migration, though I'd like to refer to it as <code>.completed_by</code>. Something that references the :user_id in my User table but is named :completed_by?</p>