Improve display when crm_mon cannot connect

I think that the output of  crm_mon is little poor
when crm_mon cannot connect.
Print_dot() already makes no sense.

```
# crm_mon
Attempting connection to the cluster...Could not establish cib_ro connection: Connection refused (111)
                             .Could not establish cib_ro connection: Connection refused (111)
                    .Could not establish cib_ro connection: Connection refused (111)
           .
(snip)
```

So I make a patch to clear ncurses screen when crm_mon cannot connect.

Before pacemaker is started
```
# crm_mon
Attempting connection to the cluster...
Could not establish cib_ro connection: Connection refused (111)
```

After pacemaker is shut down
```
Reconnecting...
Could not establish cib_ro connection: Connection refused (111)
```

I tried to implement showing running status such as print_dot() on ncurses,
but I cannot :(