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

beacon_node/beacon_chain/test_harness/src/lib.rs

@@ -1,5 +0,0 @@
-mod beacon_chain_harness;
-mod validator_harness;
-
-pub use self::beacon_chain_harness::BeaconChainHarness;
-pub use self::validator_harness::ValidatorHarness;