Add social media cards, try 2

[itsthejoker]

Relevant issue: #151

Description:

So it turns out that Twitter doesn't support SVG images -- we need to pass it something else instead. This adjustment adds a PNG version that's formatted to their standards; I don't actually know if it'll work, but it's worth a try.

Screenshots:

Almost there!

Checklist:

• [x] Code Quality
• [ ] Pep-8
• [ ] Tests (if applicable)
• [x] Success Criteria Met
• [ ] Inline Documentation
• [ ] Wiki Documentation (if applicable)