title: Can the Ecto schema field name different from column name?
body: <p>I've got a legacy database that I'm trying to pull into Ecto.  In it there's an <code>orders</code> table which has an <code>order_status_id</code> column.  <code>order_status_id</code> maps to a set of constants in the legacy system.</p>
  
  <p>I'd like to have the <code>MyApp.Order</code> struct contain an <code>order_status</code> field, which has a custom type that converts the integer IDs to meaningful atoms.  I've got the custom type working, but I can't figure out how to map a field named <code>order_status</code> to a column named <code>order_status_id</code>.</p>
  
  <p>The legacy system is still online and using the database, so changing the DB schema is not an option.  Is there any way to get this working?</p>