Create Sections for and Update Team Photos

[joel99]

3 months overdue, but the hackgt team has changed and we need new photos. New designs are eventually in the works, but for now create sections for each subteam (tech, design, ops, marketing, codirectors?) and place everyone's regular photo. The relevant file is at _pages/about.html and the corresponding assets path. Assets found on the gdrive (more instructions in slack channel).

For section headers, we're pending design, but likely just white header text and a white section divider. Make sure this is responsive.