Add containers around the input fields to be more flexible in formatting the elements.

To be more flexible in formatting the form in CSS, a container around the label and input would be helpful. On line 160, 218, 251, 271, 294 maybe a special class based on the input-type (checkbox, radio, ...) may be helpful too - but I am not really into Wordpress :)
Merge pull request #21 from LukyLuke/patch-1

Add containers around the input fields to be more flexible in formatting...