Event success report dashboard

[nukeador]

A way to report about past events by event owner is needed, so we can know how was the event and do some metrics.

We need a list of information that the owner should fill after the event.

[nukeador]

For graphs: http://code.shutterstock.com/rickshaw/

[nukeador]

Initial /stats page in dea3b99

@rlr Probably I will need more doc about rickshaw since I can't find how to do very simple stuff like displaying on hover each event name (each bar should have a different name).

[nukeador]

For some reason after applying sandbox theme, rickshaw is not loading anymore in /stats

[11:37:52.770] ReferenceError: Rickshaw is not defined @ https://eventos.mozilla-hispano.org/stats/:304

[rlr]

i'll take a look!

[nukeador]

Probably it's also a good idea to have per event stats using https://eventos.mozilla-hispano.org/XX/event-name/stats/

Such as:
Registrations per day
Attendees vs confirmed ratio
...

[rlr]

Pull request with a couple of fixes for the stats page: #36