Use howto-components for examples

[jeffposnick]

The components at https://github.com/GoogleChrome/howto-components are much nicer than what we're using right now for /examples.

CC: @surma to confirm that they're ready to be used.

[surma]

First paragraph from the README: “They are explicitly NOT a UI library meant to be used in production.”

That being said, feel free to use them as a starting point and ship them. But be warned that we haven’t put any efforts into supporting older browser versions or excessive testing across browsers.

Howto-Components are solely educational and will be consumed by reading the section on WebFundamentals that is about to launch.