API server for MockingFish app

TODO: Create own copy of ffmpeg for use with build pack When configuring, must: heroku buildpacks:set https://github.com/ddollar/heroku-buildpack-multi.git

To upload a clip: curl -H "Content-Type: audio/mpeg" -F clip=@"javascript-soundbite.mp3" http://127.0.0.1:5000/clips

To create a mix: curl -d "{ "video":"no-stop-it.mp4", "splices":[{ "audio":"javascript-soundbite.mp3","location":1 }] }" http://127.0.0.1:5000/mixes

Issues: In mix post, errors aren't sent to client (e.g. for malformed input)