Create initial components

Create initial components, testing framework & some tests

Status: **Opened for visibility**
Reviewers: @jeffkamo @kpeatt, @scalvert

## Changes
- Add grunt/bower config (sass + autoprefixer, watch task).
- Add initial utilities: dimension (width/height), layout, spacing, text, visibility.
- Add initial components:
    - Align (vertical alignment)
    - Arrange (common flexbox use cases)
    - Button (cross-element base styles)
    - Grid (simple layout grid)
    - Media (media object)
    - Ratio (intrinsic ratios)
    - Stack (building blocks for stacked lists)
    - Test (wrapper for visual testing of other components)
- Add testing framework:
    - Add fixture CSS (incl. import Test component).
    - Determine fixture HTML (no template yet)
    - Add placeholder branding for Stencil..
    - Configure grunt to build test CSS.
- Add tests for Align, Arrange, Button, Grid, Media and Stack components.
- Add tests for dimension and layout utils.

## Notes
- Much of this is based on SUIT CSS. See https://github.com/suitcss/suit/blob/master/doc/README.md for an overview of the philosophy.