bump nix to 0.14 to fix compilation issues

Author: ryankurte

Cargo.toml

@@ -15,6 +15,6 @@ use_tokio = ["futures", "tokio", "mio-evented"]
 
 [dependencies]
 futures = { version = "0.1", optional = true }
-nix = "0.10.0"
+nix = "0.14.0"
 mio = { version = "0.6", optional = true }
 tokio = { version = "0.1", optional = true }