title: whereBetween Dates in laravel 4 eloquent
body: <p>I have a query like that</p>
  
  <pre><code>SELECT * FROM `sp_price` WHERE (`from_date` between '2014-08-15' and '2014-09-18') || (`to_date` between '2014-08-15' and '2014-09-18')
  </code></pre>
  
  <p>Now how I can convert this query in <code>laravel 4</code>. I use <code>Eloquent</code></p>