Display message for unresponsive minions

In response to Issue #7084 which wanted a way to show unresponsive minions without the overhead of --verbose.  This might be a start.  It adds a --show-timeout option (which I am happy to rename if we think of something better. show_unresponsive is one alternative.)

 I only changed the get_cli_event_returns function in the client.  Two other very similar looking functions, get_cli_returns and get_cli_static_event_returns, may also need to be changed but I wasn't sure.