remove trailing whitespace
allow hidden elements to be validated via new `hiddenElementSelector` option

bValidator by default skips over hidden elements via the `:hidden` selector.
This created problems when wanting validation to run on hidden inputs when using
libraries like chosen (http://harvesthq.github.io/chosen/).

This commit adds a new option, `hiddenElementSelector`. Pass it in with your other
bValidator options. This should be a selector for hidden elements that you want
to be validated. For instance, with chosen, you would pass:

	$('form').bValidator({
		hiddenElementSelector : 'select'
	});

Or you could be more specific with the selector to just run on chosen selects.

	$('form').bValidator({
		hiddenElementSelector : 'select.chosen-select'
	});

bValidator needs an element to figure out where to place the validation error tooltip.
When the element is hidden, the tooltip can't be placed properly. To get around this, we
need to wrap our hidden elements with a `span` tag, or whatever other visible element
of your choosing. The code will take the immediate parent of any hidden elements to help
place the tooltip.

The css update on the tooltip container adding a `z-index` was required to show
validation errors on top of chosen selects.
add README with notes about new `hiddenElementSelector` option