title: cakePHP is escaping field names, as strings, in BETWEEN condition
body: <p>Cake is escaping the <code>Contract.start_date</code> and <code>Contract.end_date</code>, rendering the query useless.</p>
  
  <pre><code>$this -&gt; Contract -&gt; find('all', array(
    'fields' =&gt; array(..),
    'conditions' =&gt; array(
       'NOW() BETWEEN ? AND ?' =&gt; array(
          'Contract.start_date',
          'Contract.end_date'
        )
     )
  ));
  </code></pre>
  
  <p>The problem is that the query that is executed is</p>
  
  <pre><code>SELECT
    &lt;fields&gt; AS Monthly 
  FROM 
    `contracts` AS `Contract` 
  WHERE
    NOW() BETWEEN 'Contract.start_date' AND 'Contract.end_date' 
  #/* field names are escaped and treated as strings */
  </code></pre>