A possible approach on #416.
slightly stricter about what is copied and what is not
Scoping all css to .chart-holder so they dont accidentally affect outside elements
Reverted special rules for embed.css. Because style-scoped isn't well supported, it'll be hard to isolate css for embedded charts only. Better fix for this will come when #503 is closed.
Merge pull request #833 from onaio/embeddable_charts

Embeddable charts