Expose field properties

- add choices to fieldHandler
- add widgetAttributes to fieldHandler
- add labelText to fieldHandler
- add errorText to fieldHandler
- add placeholder to fieldHandler

![](http://38.media.tumblr.com/537f85606c0a87d718a7ab28cf946106/tumblr_mktn2jXwIy1s9ney2o1_400.gif)