Revert rust-lang#1501 in a really roundabout way

The author of ring has chosen to yank all versions of that crate other
than the most recent. This has had the effect of making it so that we
cannot modify our `Cargo.toml` without breaking the build. The long term
fix will be to get us on the latest version of cookie (which requires
updating some unmaintained dependencies). I haven't looked into how much
work that will be beyond confirming that it is not as simple as just
changing the version number.

Right now, this is blocking anything that requires updating an existing
dependency, or adding a new dependency. So this is a quick fix to get
our builds working again until we have the time to sort out updating
everything between us and ring.

Unfortunately, this isn't just as simple as reverting rust-lang#1501, since
`[patch]` doesn't force cargo to resolve to yanked versions. It'll
instead resolve to really old versions of `cookie` in an attempt to
remove `ring` from our dependency tree. So I've instead had to fork
cookie, and change its dependency on Ring to use what we had prior to
 rust-lang#1501.

Author: sgrif

Cargo.lock

@@ -89,3 +89,6 @@ tokio-service = "0.1"
 dotenv = "0.11"
 diesel = { version = "1.3.0", features = ["postgres"] }
 diesel_migrations = { version = "1.3.0", features = ["postgres"] }
+
+[patch.crates-io]
+cookie = { git = "https://github.com/sgrif/cookie-rs.git", branch = "v0.9" }