[WOL] Add a command to ping the computer

[Vexed01]

What cog is this feature request for?

WOL

Describe the feature request in as much detail as possible

Add a command to ping the host computer, and respond to the user whether or not it's online.

The best way to do this would probably be through calling a shell command, though if there's a library then that might be nicer.

This is one of my Hacktoberfest issues, which anyone may take without needing to ask me directly, and if not done I will get around to doing them in the coming months.