Publish new version to crates.io

[dignifiedquire]

The version here is pretty outdated https://crates.io/crates/sapling-crypto, it would be great to have a new version published so we could depend on that instead of the git repo here.

Background: Trying to publish https://github.com/filecoin-project/rust-proofs to crates and are currently blocked on this dependency for doing so.

Thank you

[ebfull]

We currently depend on a forked version of the blake2-rfc crate which exists only in a git repository, so we can't push to crates.io. So either

1. they accept Personalization support cesarb/blake2-rfc#9
2. we fork it and publish a new crate
3. we bring their crate into our tree

[str4d]

4. We switch to another BLAKE2 implementation that has personalization support (e.g. the blake2 crate once Add support for Persona and Salt to Blake2 RustCrypto/hashes#75 is closed).

[str4d]

Update: this will no longer happen, because we have successfully refactored this crate out of existence in zcash/librustzcash#104. Users of this crate should migrate to the next versions of bellman, zcash_primitives, and zcash_proofs when they are published (which should be soon - follow this milestone for progress).

[str4d]

As an additional note, the Jubjub and Pedersen hash circuit code was temporarily moved into zcash_proofs (and the non-circuit code into zcash_primitives) because it requires additional refactoring. It will eventually move either into bellman or a companion crate.