Added "optionsFunction" to config

Instead of saving the options as array, completely will run the function given in the optionsFunction attribute of the config object and use the output array as the options for this textInput.

A bit of code to illustrate why this may be wanted:

```html
<html>
<head>
  <script src='/js/complete.ly.1.0.1.js'></script>
</head>
<body>
<div id='div1' style='border:1px solid #999;'></div>
<div id='div2' style='border:1px solid #999;'></div>
<script>
function options() {
  // default values
  var ops = ['cocoa','coffee','orange'];
  // do some logic and change to alcoholic beverages.
  if (true)
    ops = ['vodka', 'whiskey', 'rum'];
  return ops;
}
var config = {
    	fontSize: '24px',
    	fontFamily: 'Arial',
    	color: '#933',
        'optionsFunction': options,
   };
completely(document.getElementById('div1'), config);
completely(document.getElementById('div2'), config);
</script>
</body>
</html>
```