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/tree_hash/examples/flamegraph_beacon_state.rs

@@ -1,4 +1,3 @@
-use tree_hash::TreeHash;
 use types::test_utils::TestingBeaconStateBuilder;
 use types::{BeaconState, EthSpec, MainnetEthSpec};
 
@@ -29,7 +28,7 @@ fn main() {
     let mut vec = Vec::with_capacity(TREE_HASH_LOOPS);
 
     for _ in 0..TREE_HASH_LOOPS {
-        let root = state.tree_hash_root();
+        let root = state.canonical_root();
         vec.push(root[0]);
     }
 }