Add support for Ubuntu...

...and maybe other unix/linux distros.

Use /dev/urandom instead of jot for a more generic approach.
Also, use aplay if afplay is not found.

I don't have a mac, so I couldn't say for sure if this still works
in them...
Merge pull request #1 from xFlatlinex/ubuntu-support

Add support for Ubuntu (and maybe other unix/linux distros)