Vendor dependencies

Let's see how I like this workflow.

vendor/autocfg/Cargo.toml

@@ -0,0 +1,24 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+name = "autocfg"
+version = "1.1.0"
+authors = ["Josh Stone <cuviper@gmail.com>"]
+exclude = ["/.github/**", "/bors.toml"]
+description = "Automatic cfg for Rust compiler features"
+readme = "README.md"
+keywords = ["rustc", "build", "autoconf"]
+categories = ["development-tools::build-utils"]
+license = "Apache-2.0 OR MIT"
+repository = "https://github.com/cuviper/autocfg"
+
+[dependencies]