Redesign: replace video with banner

[machow]

Currently we have a video as a first piece above the fold, but it is not clickable. Let's replace it with a nice static image.

Old vs New

Old:

New:

Details

• "Join Us" link should go to https://codeforphilly.org/volunteer

[machow]

Kat mentioned she likes the video -- I'm going to close for now!