[Projects Page Backend] Dynamically populate projects from Contentful

[justinsheu]

TODO: split into multiple issues?

• Projects page ([Projects Page] Grid of projects quarters #140), projects quarter page ([Projects Page] Projects quarter page #142), and individual project page ([Projects Page] Individual project page #143) should all be dynamically populated from Contentful
• Write new function to retrieve list of quarters and their descriptions from Contentful
• Write new function to retrieve list of projects along with their members, description, and logo, given a quarter
• Write new function to retrieve a specific project's members, description, images, demo link, and demo slide link
• Modify projects page, projects quarter page, and individual project page to call these new functions instead of the dummy API call functions to populate those respective pages