title: Waterline ORM equivalent of insert on duplicate key update
body: <p>I have a table user_address and it has some fields like</p>
  
  <pre><code>attributes: {
    user_id: 'integer',
    address: 'string' //etc.
  }
  </code></pre>
  
  <p>currently I'm doing this to insert a new record, but if one exists for this user, update it:</p>
  
  <pre><code>UserAddress
    .query(
      'INSERT INTO user_address (user_id, address) VALUES (?, ?) ' +
        'ON DUPLICATE KEY UPDATE address=VALUES(address);',
      params,
      function(err) {
         //error handling logic if err exists
      }
  </code></pre>
  
  <p>Is there any way to use the Waterline ORM instead of straight SQL queries to achieve the same thing? I don't want to do two queries because it's inefficient and hard to maintain.</p>