Merge #141: Add a disabled rustfmt.toml

bd59192 Add a disabled rustfmt.toml (Tobin Harding)

Pull request description:

  We do not currently use `rustfmt`, this is a nuisance for devs who routinely work on code bases that do use rustfmt who often have their editors set to format on save. We can make the life of such devs much better by explicitly disabling formatting using `rustfmt.toml`.

  ref: https://rust-lang.github.io/rustfmt/?version=v1.4.38&search=#disable_all_formatting

ACKs for top commit:
  apoelstra:
    ACK bd59192

Tree-SHA512: 0a3a11f305f8e556ae9ba511c2057dda159b85ee9f44d78305b4d473156ef033da98ce63c8917aa0eb9bba26565180777e8562fe97933452246de9686edeecd8

rustfmt.toml

@@ -0,0 +1 @@
+disable_all_formatting = true