Create Checkins when user checks in

This simply tracks where they've been, and any food they eat will get attached.
Separating the checkin from the food lets us potentially report multiple items
at one spot.
Create Food model

This stores what a user ate and how much they liked it.
Don't let Foursquare reply failures abort saving

Since `after_create` happens inside the DB transaction, a failure posting our
checkin reply causes a rollback. `after_commit` waits until everything is saved.
Create basic food entry form

The checkin reply clicks through to here, where the user can tell us what they
ate.
Link connected story to rating URL

Now when a user taps on the story we post, FourSquare will load a webview with
the "What did you eat?" form.
Style food input form

Thanks to @pattycreates for the design and smileys!
Use individual images for smileys

I was too optimistic about mobile resolutions. Making each its own image lets
them be responsive to the window width.
Save Food objects

Doesn't do anything smart for the user yet, but we store what we need.
Redirect the user back to Foursquare

Or to `/` if there's nothing else to do.