Initial commit for wallet

[Schmavery]

This is a rough framework for the wallet app, running on electron + reasonreact + graphql
Exposes a server from the daemon that serves graphql (a single queryable value) from localhost:8080/graphql. The schema of the graphql is generated and checked in on the client side.

The layout itself is basically just a made-up proof of concept right now.

Some work is remaining to hook up CI probably.

Adds opam dependency on:

• graphql-async.0.9.0
• graphql-cohttp.0.8.0

Some future work:

• Move server graphql schema to its own library (and hook it up to real things)
• Look into bs-css (https://github.com/SentiaAnalytics/bs-css)
• Move the bs-electron fork to codaprotocol github org

[bkase]

Can you make CI do refmt and die if it's not?

[bkase]

And try to build the daemon to get the schema if it's not too slow

[Schmavery]

I think we should check in the schema.json because it's a clearer definition of the schema that's consumable from non-ocaml code/tooling. I've talked to some other people using this graphql setup and that seems to be the approach they're taking, fwiw.
If this design becomes problematic, we can always change it.

Will add the refmt check though ofc