Factor rule outside media queries.

It was a rule that wasn't dependent on screen size at all, and was
simply being duplicated unnecessarily. So I took it out.
Add missing variables for buttons, type, and visibility to _setting.scss.
fix bug that makes background color appear on hover on side nav
Docs fix for Alert Box examples. Fixes #3664

The advanced examples for Alert Boxes were missing the data-alert
attribute in the example code
Update README.md
Modified FastClick initialization to delay until document ready.
Fixed spelling error
Fix sticky topbar typo.
Bump topbar version to 5.0.3
Bump core version to 5.0.3
Merge branch 'master' into move-end-selector
Merge pull request #3662 from maxbucknell/move-end-selector

Factor rule outside media queries.