message: Remove runtime panic from services:pool::Pool.
diff: @@ -325,10 +325,10 @@ impl Pool {
  })
  }
  - pub fn send_tx(&self, cmd_id: i32, json: &str) {
  + pub fn send_tx(&self, cmd_id: i32, json: &str) -> Result<(), PoolError> {
  let mut buf = [0u8; 4];
  LittleEndian::write_i32(&mut buf, cmd_id);
  - self.cmd_sock.send_multipart(&[json.as_bytes(), &buf], zmq::DONTWAIT).expect("send to cmd sock");
  + Ok(self.cmd_sock.send_multipart(&[json.as_bytes(), &buf], zmq::DONTWAIT)?)
  }
  }
  @@ -474,7 +474,7 @@ impl PoolService {
  let cmd_id: i32 = SequenceUtils::get_next_id();
  self.pools.try_borrow()?
  .get(&handle).ok_or(PoolError::InvalidHandle("No pool with requested handle".to_string()))?
  - .send_tx(cmd_id, json);
  + .send_tx(cmd_id, json)?;
  Ok(cmd_id)
  }
  @@ -581,7 +581,7 @@ mod tests {
  cmd_sock: send_cmd_sock,
  };
  let test_data = "str_instead_of_tx_json";
  - pool.send_tx(0, test_data);
  + pool.send_tx(0, test_data).unwrap();
  assert_eq!(recv_cmd_sock.recv_string(zmq::DONTWAIT).unwrap().unwrap(), test_data);
  }
  