Vendor dependencies

Let's see how I like this workflow.

vendor/signal-hook-mio/Cargo.toml

@@ -0,0 +1,95 @@
+# 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]
+edition = "2018"
+name = "signal-hook-mio"
+version = "0.2.3"
+authors = [
+    "Michal 'vorner' Vaner <vorner@vorner.cz>",
+    "Thomas Himmelstoss <thimm@posteo.de>",
+]
+description = "MIO support for signal-hook"
+documentation = "https://docs.rs/signal-hook-mio"
+readme = "README.md"
+keywords = [
+    "signal",
+    "unix",
+    "mio",
+]
+license = "Apache-2.0/MIT"
+repository = "https://github.com/vorner/signal-hook"
+
+[package.metadata.docs.rs]
+all-features = true
+rustdoc-args = [
+    "--cfg",
+    "docsrs",
+]
+
+[dependencies.libc]
+version = "~0.2"
+
+[dependencies.mio-0_6]
+version = "~0.6"
+optional = true
+package = "mio"
+
+[dependencies.mio-0_7]
+version = "~0.7"
+features = [
+    "os-util",
+    "uds",
+]
+optional = true
+package = "mio"
+
+[dependencies.mio-0_8]
+version = "~0.8"
+features = [
+    "net",
+    "os-ext",
+]
+optional = true
+package = "mio"
+
+[dependencies.mio-uds]
+version = "~0.6"
+optional = true
+
+[dependencies.signal-hook]
+version = "~0.3"
+
+[dev-dependencies.mio-0_7]
+version = "~0.7"
+features = [
+    "os-util",
+    "os-poll",
+    "uds",
+]
+package = "mio"
+
+[dev-dependencies.serial_test]
+version = "~0.5"
+
+[features]
+support-v0_6 = [
+    "mio-0_6",
+    "mio-uds",
+]
+support-v0_7 = ["mio-0_7"]
+support-v0_8 = ["mio-0_8"]
+
+[badges.maintenance]
+status = "actively-developed"
+
+[badges.travis-ci]
+repository = "vorner/signal-hook"