Handle timeout of miami-transit-api

[qtrandev]

Recently we've been having issues where the server at http://miami-transit-api.herokuapp.com/api/Buses.json times out and we don't get any data back.

This a server problem, but we need to be able to handle this better. Display an error message if the server times out and we don't get any data back.

[qtrandev]

@dannav If you want, fix this issue (CodeforSouth/miami-transit-api#13) on the server side or make the client side handle timeouts better. Make commits only to "dev" branch - you have write access. I'll pull into master and gh-pages branches.