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

eth2/utils/eth2_hashing/fuzz/fuzz_targets/fuzz_target_hash.rs

@@ -0,0 +1,9 @@
+#![no_main]
+#[macro_use] extern crate libfuzzer_sys;
+extern crate hashing;
+
+use hashing::hash;
+
+fuzz_target!(|data: &[u8]| {
+    let _result = hash(data);
+});