Changed the simple_form class to properly convert variables to their htm...

I was having issues because simpleform did not use the formencode.Validator.from_python methods when filling the HTML forms with values. I made changes so that this is the case - so that the system properly switches between the python-style and html-style representations or variables. 

My changes could be made better though, as in a couple of places we convert to python representation, back to html representation (see line 198 in the latest update). It seemed like I would have to rewrite the whole function to avoid this.