Publish ssz_types (and deps) to crates.io (#468)

* Rename `hashing` crate to `eth2_hashing`

* Add license, desc to eth2_hashing Cargo.toml

* Remove merkle root from eth2 hashing

* Remove old benches folder (zombied from old branch)

* Add docs to eth2_hashing

* Prepare tree_hash for publishing on crates.io

* Update deps to use crates.io instead of paths

* Update all crates to pull ssz from crates.io

* Remove cached_tree_hash, add patches to manifest

* Fix compile error in benches

* Remove unused code

* Fix fake_crypto compile error

beacon_node/client/Cargo.toml

@@ -12,7 +12,7 @@ rpc = { path = "../rpc" }
 rest_api = { path = "../rest_api" }
 prometheus = "^0.6"
 types = { path = "../../eth2/types" }
-tree_hash = { path = "../../eth2/utils/tree_hash" }
+tree_hash = "0.1"
 eth2_config = { path = "../../eth2/utils/eth2_config" }
 slot_clock = { path = "../../eth2/utils/slot_clock" }
 serde = "1.0.93"