Update to iron-flex-layout

[addyosmani]

r: @nevir

Minimal set of changes needed to get the demos/package working atm. Summary:

• Define resolution for observe-js so you get the correct observe-js.html import
• Update to iron-flex-layout classes otherwise the demos fail out of the box
• Bumps to latest paper-styles

[nevir]

Thanks!

[addyosmani]

npnp!