Remove field data from snippet store

The store doesn't know about the fields in the data, and it shouldn't. So that logic is back where it belongs.
Move the flake config into the correct file
Pass the page/page count to the UI
Move flake dep to correct rebar.config
Use binaries for strings and Jiffy JSON

In my ignorance I was using strings all over the shop when I should have instead been using binaries. This commit fixes this and all the "string" value use binaries.

mochijson2 has been stripped out and instead we're now using Jiffy, as it's a bit faster (NIF) and I like the syntax a bit more. Encoding of atoms is completely gone now, all elements in the JSON are just binaries. As a result, csd_json has been ditched.