Add Meetup.com integration to front page

[dmsnell]

Related to #65

We don't currently have our current meetup information listed on our website, but Meetup.com has an API to embed that in other websites. We could pull in that information and add a button on our site and I believe that doing this would improve the discoverability of meetup info.

Some brigades have these embeds on their front pages.

cc: @meiqimichelle