Strip out old code

All of these files have been moved to either:

- https://github.com/sigp/lighthouse-beacon
- https://github.com/sigp/lighthouse-validator
- https://github.com/sigp/lighthouse-common

For rationale, see: https://github.com/sigp/lighthouse/issues/197

eth2/utils/hashing/Cargo.toml

@@ -1,8 +0,0 @@
-[package]
-name = "hashing"
-version = "0.1.0"
-authors = ["Paul Hauner <paul@paulhauner.com>"]
-edition = "2018"
-
-[dependencies]
-tiny-keccak = "1.4.2"