Fix: tools: Properly close ncurses output in crm_mon.

When clean_up_connections is called at the end of crm_mon, one of the
things it does is call mon_cib_connection_destroy. This calls out->err.
However, this happens after curses has been shut down. The result is
the terminal doesn't work as expected after crm_mon quits.

Instead, move all the curses shutdown code into curses_finish. This
function gets called almost as the very last thing, hopefully after any
other output could possibly take place.

I did a little bit of reorganization around how out->finish is called at
the end of crm_mon too, just to make everything happen in one place.