title: updating options on signature pad plugin
body: <p>I am trying to update the options on Signature Pad but it does not seem to be working.</p>
  
  <p>The option that I am trying to update is the pen colour, i have created a button that once clicked on should update the object and change the pen colour.</p>
  
  <pre><code>var options = {
      drawOnly: true,
      defaultAction: 'drawIt',
      validateFields: false,
      lineWidth: 0,
      output: null,
      sigNav: null,
      name: null,
      typed: null,
      clear: 'input[type=reset]',
      typeIt: null,
      drawIt: null,
      typeItDesc: null,
      drawItDesc: null,
      penColour: '#000',
  };
  
  var api = $('form').signaturePad(options);
  
  $('.green').click(function(){
      api.clearCanvas();
      $.fn.signaturePad.penColour = '#00FF00';
  });
  </code></pre>
  
  <p>any ideas?</p>