Integrated Gallery into DataCultures: images and videos load properly

https://jira.ets.berkeley.edu/jira/browse/CYB-80

Initial integration of Gallery into DataCultures

Styling will be completely revamped by @ericayin, at the moment only functionality is of core value
@NolanChan can we use an `iframe` here instead? That should allow people with HTML5 enabled browsers to have a more accessible video.

See https://support.google.com/youtube/answer/171780?hl=en - old / new embed code.