Move the crates-io crate to a crates directory

That way when we add more crates we've got a place to put them!

Cargo.toml

@@ -21,7 +21,7 @@ path = "src/cargo/lib.rs"
 atty = "0.2"
 byteorder = "1.2"
 bytesize = "1.0"
-crates-io = { path = "src/crates-io", version = "0.26" }
+crates-io = { path = "crates/crates-io", version = "0.26" }
 crossbeam-utils = "0.6"
 crypto-hash = "0.3.1"
 curl = { version = "0.4.21", features = ['http2'] }