Additions and bug fixes

- Added support for form fields.
- Added escape-key support for dismissal.
- Added a dismiss event.
- Updated documentation with destroyOnClick, destroyOnEsc,
onFeatureFail, onDismiss and preventScroll.
- Replace overlayClass with a classname?
- Updated the examples.
- Changed the behaviour of the onOverlayClick to get rid of a bug that
dismisses the view when the button that instantiates the huer view is
doubleclicked.