Show storyshots in UI

[SpaceK33z]

It would be great if the storyshot tests were visible in the Storybook UI, like storybook-addon-specifications. At the moment the storyshots are not in the same "development flow", because you have to open your terminal each time to see the storyshots.

A next step would be to have a button you can click to update the storyshot if it failed.

I might be able to work on this during the holidays. Just to start of the discussion, how could I implement this (roughly)?

The current idea I have is to hook into the Storybook server (which should be possible since storybookjs/storybook#435) and install a WebSocket. Storyshots would use this WebSocket to push the failed / successful storyshots. On the client, there is storybook-channel-websocket to listen / push things to the WebSocket.

Or would it be cleaner to make a separate addon for this? I think all storyshots users would want this, so that's why I'm leaning towards adding it in storyshots at the moment.