Layout responsive events list and event details pages

As part of #138 two new pages are being added to laddr:
- Browse Events: http://laddr-v2-dev.poplar.phl.io/events
- Event Details
- Upcoming event we'll be promoting: http://laddr-v2-dev.poplar.phl.io/events/city-as-a-service-2016
- Recent event with full schedule input: http://laddr-v2-dev.poplar.phl.io/events/sustainability-2015

Here's a fully-featured event on the old site we're deprecating: Almost fully-features event page from past hackathon on the appsforphilly site we're deprecating: http://appsforphilly.org/events/transportation-2015

The most immediate use case will be using the direct link to the upcoming hackathon for promoting it. Key elements include:
- Prominent date, location
- Long markdown content area with multiple headlined main sections
- Detailed one-day or multi-day schedule
- Small list of subpages with detailed information about the event
- Gallery of sponsor logos
- Idea board or preview with link to full idea board page
- Gallery of RSVPd attendees
- List of links to projects founded for the event

If it sounds like a party flyer, it kind of is... but maybe could be less so

Empieza revisando las URL de Browse Events y Event Details, y luego compáralas con la página de eventos obsoleta de appsforphilly.org. Se considera terminado cuando haya páginas responsivas de lista y detalle de eventos que cubran la información destacada del evento, el contenido, los horarios, las subpáginas, los logotipos de patrocinadores, los asistentes, las ideas y los enlaces a proyectos descritos en el issue.

Escrito por el modelo de indexación a partir del texto del issue.