form onsubmit method modified

#Modification:
1. _getInputElt method added to create a HTML imput element and return
to the calling function
2. onsubmit method for HTMLFormElements changed by addEventListener and
later addEventListener method of HTMLFormElement is wrapped so that CSRF
token doesnot interfere with any logic implemented by developer
Merge pull request #2 from mebjas/master

form onsubmit method modified