title: Impossible to edit form with CasperJS when it is not empty
body: <p>I use CasperJS for form editing but I have a problem. When I have content in input, CasperJS can't edit this input.</p>
  
  <p>Here, my script: </p>
  
  <pre><code>this.sendKeys(
      x('(//input[contains(@id, "DateSignatureContrat")])[last()]'), 
      '31/08/2015'
  );
  </code></pre>
  
  <p>If I have a value on input, CasperJS doesn't change the value to 31/08/2015 but if this input is empty, CasperJS can.</p>