Fix duplicated ids

The id `right-label` is duplicate, and colides with doc/includes/form/examples_form_inline_labels.html. To replicate the issue just click in the `label.right.inline` in http://foundation.zurb.com/docs/components/forms.html
Move hyphen outside of column loops

Fixed an issue with modifying loops in @mixin grid-html-classes(),
where starting the loops at zero would yield classes like
".small-push0" instead of ".small-push-0". This is due to the hyphen
being inside #{-$i}, which evaluates -0 (negative zero) as 0. Moving
the hyphen outside of the braces restores the hyphen. (And from a
pedantic standpoint, the hyphen is used as a hyphen in the class name,
not as an indication of negation.) This syntax is already in use for
offset classes.

Also increases loop range to include 0 through 11 in push/pull/offset
classes, which are necessary for overriding.