feat #739 extract css.Units util

Extract existing unit manipulation tool.

Add some new methods for reverse direction calculations and also some
helper methods needed for IE8- polyfill of
`getComputedStyle(width|height)`.
They're all in this class instead of `utils.Dom` to avoid circular dependencies.

Also fix some small issues:
- `font-size` -> `fontSize` in a check
- `fontSize` returned can be non-pixel in IE; taken into consideration now
fix #739 consider borders/paddings in getStyle(width|height) in IE
v1.4.10
feat #742 Google Map is now activated over ssl when needed, regardless of the user

The feature is available for all users, from Google Map V3 : https://developers.google.com/maps/faq#ssl

Close #742
fix #725 Improving test stability

test.aria.touch.widgets.dialog.events.DialogAnimationsTestCase and
test.aria.widgets.container.tooltip.TooltipTestCase were randomly
failing because of timeouts (which were sometimes too small).
This commit replaces the timeouts with calls to waitFor.

Also, renames some tests which had classpath parts starting from
uppercase.

Close #741
refactor Remove dead code

Remove variables that are created but never used (in some cases, remove
the variable entirely; in some case, just call the method without storing
the result).

Add JSHint build-time check (for `src` files only) for declared but unused vars.

Also, fixes a minor issue that landed in
https://github.com/ariatemplates/ariatemplates/commit/107507a30d0407e46bcbf6dea3cf31ee28c43928#commitcomment-4166998

Close #710. Close #743.
feat #745 enable `getComputedStyle` for IE9+

Close #745.
refactor some positioning/viewport calculations

1) don't recalculate the viewport size in `onViewportResized` in Dialog,
take it from event data
2) round to full pixels in `utils.Dom.calculatePosition`
(`getBoundingClientRect` returns floats)

Close #677.
feat #714 custom padding for the `pad` modifier

Now the `pad` modifier accepts third parameter which is the padding
string. By default it's `&nbsp;` if not provided.

Close #714. Close #724.
fix #749 enable VisualFocusTest in IE8