Previously when the `diameter` prop of the `jazzicon` component was
changed, the new diameter would be ignored. The jazzicon is now
redrawn upon each change, as you would expect.
I don't think it's possible for this bug to manifest itself in the
extension. This was discovered through tinkering with the Storybook
for this component.
* Use ref instead of findDOMNode in jazzicon component
The jazzicon component was using `findDOMNode` to get the DOM node for
the main div returned by the component, which is generally not
recommended. Instead a ref is now used.
* Update Jazzicon to v2
This version drops the dependency upon `raphael`, and no longer uses
the function `createSVGMatrix` which was causing unit tests to fail
(because it's not supported by jsdom).
