Rust documentation is incorrect.

[ChristopherMacGown]

I had hoped to publish the rust package to crates.io following the merge of #12, but unfortunately am prevented by rust-lang/crates.io#1142 . Ideally, someone in the @metaparticle-io organization would be able to publish it by:

1. Successfully logging in with github on https://crates.io
2. Obtaining an API Token at https://crates.io/me
3. Packaging and publishing with:

# cargo login $API_KEY
# cargo package
# cargo publish

Less ideally, lines 8-14 in the README should be changed to:

Clone the metaparticle-io/sync repository locally via 
`$ git clone https://github.com/metaparticle-io/sync`
and add the following to your `Cargo.toml`

[dependencies]
metaparticle_sync = { path = "../path/to/metaparticle_sync/rust" }

[brendandburns]

I'll see about pushing the crate.

Thanks
--brendan