proxy: Fix bench tests and require bench tests in CI (#1038)

b3170af changed the DstLabels api, but the bench test was not updated
accordingly.

Furthermore, since bench tests require a nightly rust version, we've
avoided running them in CI. This makes it easy for these tests to break, however.

This updates the benches/record.rs. Additionally, in CI, we pin the rust nightly'
version to a known-good version so that we can reliably run these bench test
without the fear of external changes breaking our build.

proxy/Cargo.toml

@@ -39,8 +39,6 @@ prost-types = "0.3.0"
 
 trust-dns-resolver = { default-features = false, git = "https://github.com/bluejekyll/trust-dns", branch = "master" }
 
-#futures-watch   = { git = "https://github.com/carllerche/better-future" }
-
 tokio-connect         = { git = "https://github.com/carllerche/tokio-connect" }
 tower-service         = { git = "https://github.com/tower-rs/tower" }
 tower-balance         = { git = "https://github.com/tower-rs/tower" }

proxy/benches/record.rs

@@ -2,7 +2,6 @@
 #![deny(warnings)]
 
 extern crate conduit_proxy;
-extern crate futures_watch;
 extern crate http;
 extern crate test;
 
@@ -44,8 +43,7 @@ where
     L: IntoIterator<Item=(S, S)>,
     S: fmt::Display,
 {
-    let (labels_watch, _store) = futures_watch::Watch::new(metrics::DstLabels::new(labels));
-    ctx::transport::Client::new(&proxy, &addr(), Some(labels_watch))
+    ctx::transport::Client::new(&proxy, &addr(), metrics::DstLabels::new(labels))
 }
 
 fn request(