Merge branch '2.0.0-wip' into feature/Grid
* converted `$one-col` to `@function one-column`
* fixed an issue that would cause the grid to break if margin was set to 0
added 1% padding to `.container`
* removed unnecessary code for footer.

* applied `min-height: 100%` to `.sticky-footer` instead of `.container`.
* fixed `$stick-footer-height` variable.
added `.container-fluid`
* added a default `$grid-gutter` value

* added `$grid-col-padding-left` and `$grid-col-padding-right` variables
rewrote `@mixin make-row`
* fixed container

* added box-sizing
Finished grid testing
Merge branch 'feature/Grid' into 2.0.0-wip