Fix HTML output arround HTMLForm's submit buttons when in vform

$html in HTMLForm::getButtons() is vrapped in a <div></div> when in
vform mode but it contains a <span> tag without its closing
counterpart, thus making the HTML invalid.

And while I'm at it: put line breaks at better places.

Change-Id: I7ffa1bdd72d95188320c1b29d1c46a5f6f434cbe
Merge "Fix HTML output arround HTMLForm's submit buttons when in vform"