component stories, init new component file-structure, refs #2182

This work adds stories for all of our components in the 'elements' dir
that are used 3 or more times. It also demonstrates a file structure in
which components and associated resources (css, tests, stories and
snapshots) are co-located in a sub-directory that has the component's
name, with the component itself being named 'index.jsx' per JS module
specifications.