Add width-auto, height-auto classes.

[ainsleyclark]

Describe the bug
Need to add width and height auto classes & at responsive breakpoints.

[ainsleyclark]

New loop in sizing page

@each $property, $abbrev in (width: w, height: h) {
	@each $modifier, $breakpoint in $grid-properties {
		@include create-mediaquery($breakpoint) {
			@each $value in $sizing-properties {
				//Rid of % in $value
				$class-value: str-replace(#{$value}, '%', '');
				.#{$abbrev}#{$modifier}-#{$class-value} {
					#{$property}: #{$value} !important;
				}
			}
			//Auto classes
			.#{$abbrev}#{$modifier}-auto {
				#{$property}: auto !important;
			}
		}
	}
}

[ainsleyclark]

Add to docs page.