Add Sponsors tier section

[tshiUCSB]

Sponsors section is where you see all the logos from sponsoring companies stacked on top of each other w/ the ones sponsoring more money more towards top w/ larger logos. The size and position of the logo vary by the tier they are sponsoring. For example, see last year's site.
The logos for companies can be found here. There are sponsors that we're still negotiating w/ rn so we'll likely be adding more logos in the future

• add section title: "Sponsors" left-aligned like the rest of the titles
• 1st row tier3 sponsors: Firebase, Invoca, Teledoc Health, COE
• 2nd row tier2 sponsors: The @ Company, Blockstack
• 3rd row tier1 sponsors: Corsair, RStudio, Repl.it, Axure
• leave at least mx-3/12 lg:mx-1/12 margin on bottom so everything's not touching the bottom of the window and also min-h-screen
• background gradient from sea-400 to sea-500
• responsive: layout and proportions between logos should stay pretty much the same regardless of screen size
• link each logo to their respective company URL that can be found here