Added comments
Inform about offline hosts at the beginning

When a host is not reachable by ping, the script now reports this when the first check fails.

Previous output (no information about 192.168.2.222 being offline):
Checking 3 hosts.
Mon May 12 22:29:46 2014: Ping succeeded for host 192.168.2.111
Mon May 12 22:29:46 2014: Ping succeeded for host 192.168.2.105

New output:
Checking 3 hosts.
Mon May 12 22:31:32 2014: Ping succeeded for host 192.168.2.111
Mon May 12 22:31:32 2014: Ping succeeded for host 192.168.2.105
Mon May 12 22:31:37 2014: Ping failed for host 192.168.2.222