Add placeholder classes to remaing utils

Status: **Opened for Review**
Reviewers: @kpeatt @ry5n @avelinet @cole-sanderson @mlworks @nastiatikk 
JIRA: **CSOPS-954**

## Changes
- Add placeholder classes (i.e. `$u-width-1of3`) to all utilities
Oh, I see. We’re *replacing* the class attr selector. This is all kind of making me feel like changing my mind about adding the placeholders to these utils. Just seems gross. If people need to work with client markup they should write their simple props (utils) themselves.