Fix JavaScript errors in the demo (closes #43)

[philipwalton]

It appears that the styling issue in #43 was caused by JavaScript errors on the page that were preventing the styles from fully loading.

I've update the code to work around these errors, but I'm a little concerned about the fact that they happened in the first place. Here's what happened:

1. Change GoogleWebComponents/google-chart@4cd73d1 introduced a new default value for the options property which broke the <google-analytics-chart> element. Arguably this change shouldn't have been introduced without a major version bump for this exact reason.
2. In <google-analytics-dashboard>, the queryUpdated event listener is getting called prior to the query property being initialized with its default value. I don't think this is WAI; it seems like it might be a bug in Polymer, though I don't have time to track down what may have caused the change in behavior.

I'm happy to have these updates merged to fix the immediate styling issue, but if someone else has an answer to the second problem above, I think it would be better to figure out the source of the problem rather than merging in a temporary hack.

[philipwalton]

@ebidel PTAL

[ebidel]

Yea that should have been a major release if it's a breaking change for consumers.

Re 2, it's probably a good idea to put the check in place like you have. Another way to guard against the timing issue is to setup a listener in attached. That way you know your properties object is ready to go at that point.

[ebidel]

LGTM