Don't pass --pids-limit for now

There should be a default value and it's not on Travis right now

Author: alexcrichton

src/docker.rs

@@ -21,7 +21,6 @@ impl Container {
                                    .arg("--cap-drop=ALL")
                                    .arg("--memory=128m")
                                    .arg("--net=none")
-                                   .arg("--pids-limit=5")
                                    .arg("--security-opt=no-new-privileges")
                                    .arg("--interactive")
                                    .arg(name)