Support embedding Maptio maps on medium

[rgoj]

Turns out medium doesn't support embedding using iframes, we'd need to integrate Maptio with embed.ly! More info here: https://help.medium.com/hc/en-us/articles/214981378-Using-embeds

This came up in onboarding with Eirini from Deep Science Ventures. Some context: https://app.intercom.com/a/apps/q3x5lnhp/inbox/inbox/conversation/106323200001746?simulator=false