message: [cluster-test] Use default port in --swarm if port is not specified
  This allows to use `--swarm --peers ip1,ip2,ip3` instead of `--swarm --peers ip1:8000,ip2:8000,ip3:8000`
  Custom port can still be specified, for example `--swarm --peers ip1,ip2:6000,ip3` is a valid command
  Closes:
  Approved by: ankushagarwal
diff: @@ -38,6 +38,7 @@ use futures::{
  future::{join_all, FutureExt, TryFutureExt},
  select,
  };
  +use libra_config::config::AdmissionControlConfig;
  use tokio::{
  runtime::{Builder, Runtime},
  time::{delay_for, delay_until, Instant as TokioInstant},
  @@ -305,6 +306,10 @@ struct ClusterTestRunner {
  fn parse_host_port(s: &str) -> Result<(String, u32)> {
  let v = s.split(':').collect::<Vec<&str>>();
  + if v.len() == 1 {
  + let default_port = AdmissionControlConfig::default().address.port() as u32;
  + return Ok((v[0].to_string(), default_port));
  + }
  if v.len() != 2 {
  return Err(format_err!("Failed to parse {:?} in host:port format", s));
  }
  