Preserve line height and bug fixes

Hey, so if you don't want any of this then let me know and I'll break them into separate pull-requests. This gist of what this PR does:

- makes resizing take into account padding. This is something jQuery does with `.width()` and `.height()` so this just adds that back in.

- Fixes a bug where we were only looking at height, and not width (we were querying on `div` which has display block instead of the inner span).

- Fix where calling `$scope.$digest()` would result in different font sizes depending if we were growing up or down. This now has us grow too big, and then subtract 1 from it.

- Add an option to preserve line-height. This is especially useful if you have things inline with each other (such as headers on a page divided into thirds) and want them to be able to shrink but still keep them inline with each other.