remove fbsource version, import github version

Summary:
This is (I think) the last step required to make rust-partial-io be github-first.

The diff was created using:
* `zbgs partial-io` and remove all instances of it in fbsource
* `hg rm common/rust/partial-io`
* add `partial-io` to `third-party/rust/Cargo.toml`
* `common/rust/tools/reindeer/vendor` to vendor
* `buck build eden/mononoke/mercurial/...` to check that it builds correctly
* `buck run //common/rust/cargo_from_buck:cargo_from_buck` to run autocargo

Reviewed By: aslpavel

Differential Revision: D23849634

fbshipit-source-id: 339fc3976cc9a0b6f10a0538d643b87797e2bc3c

eden/mononoke/mercurial/bundles/Cargo.toml

@@ -43,6 +43,6 @@ tokio-io = "0.1"
 mercurial_types-mocks = { path = "../types/mocks" }
 failure_ext = { git = "https://github.com/facebookexperimental/rust-shed.git", branch = "master" }
 fbinit = { git = "https://github.com/facebookexperimental/rust-shed.git", branch = "master" }
-partial-io = { git = "https://github.com/facebookincubator/rust-partial-io", branch = "master", features = ["quickcheck_types", "tokio"] }
 assert_matches = "1.3"
+partial-io = { git = "https://github.com/lukaspiatkowski/rust-partial-io", rev = "9cab8b8a2b41f2c78aa109dcba5d00212cbe43cf", features = ["quickcheck_types", "tokio"] }
 tokio-compat = "0.1"