Unity component height

New variables:

1. $textfield-min-height - Effect the content height of component.
2. $component-inner-height - The larger one between $py-line-computed and
$textfield-min-height.
3. $component-outer-height - Component content height with outer padding gaps
and border width.

Feature adjusted:

1. Remove .indent-left-* and .indent-right-*, only and set default indent width
as 20%(a column width in elastic-grid.css)
2. Extend default modifiers(e.g. .mini, .naked) in labels, .icon, .message,
headline and .breadcrumb.
3. Unity component height for every base component.Major of them got extended
.mini modifier.
wip Update details
wip - Add component .pointer-* and .tip
Add progress
Unity normal height, mini height, extra mini

1. Simplify modifier name on .progress.
2. Unity extra mini component height.
Fixed incorrect height of .message and .link

1. Make up lost top border as top padding.
2. Adjust smaller size for .message-icon.
3. Fixed .link not inherit line-height.
Fixed bug highlight cover by button

1. Add new Class $GROUP & $GROUP-ITEM.
2. Add new item Class $ITEM-*-LOOSE/TIGHT.
3. Unity Class names in ALL-CAPS.
4. Update collection style by new stuff.
WIP