Bug 1070001: Re-org Stylus - Columns

Changed columns to have 3 decimals of accuracy.

LTR now lines up on left side and doesn't need negative margin to compensate.
Merge pull request #2799 from stephaniehobson/BUG-1070001-reorg-stylus-cols

Bug 1070001: Re-org Stylus - Columns
Fix Bug 1018596: Previous and Next Buttons

Changed the previousPage and NextPage macro to include the class "neutral" so we can remove the custom styles making these blue. They still need the styles for positioning though. Yay less code!

To test: BEFORE you check this branch out, edit the previousPage and next Page macro to include the "neutral" class on the button. Have a look at a page using the macro and confirm for me that it is okay to have that class on the buttons before the style sheet change is in place.

Then checkout the branch and have a look at the result of the new styles.
bug 1084003 - require two peer review and at least one owner for database migration changes
Bug 1072493 - Add initial testing suites
Bug 1072493: Move UI tests and improve docs
Bug 1082853: Configure CSSLint and validate MDN CSS

Made a more decerning vendorize mixin with lookup tables for values.
Made a mixin for creating rgba fallbacks.
Remove table.activity which was presumably added back in during a merge somewhere).
Validate CSS, mostly working with outlines.