Added Console Logging to HaaS

This patch adds console logging to HaaS by running ipmitool subprocesses that
log to files.  There is now an API call 'show_console' that displays the
contents of the console log to the user.  Log files are securely deleted when
nodes have a change in ownership.
I don't think we need to `shred` it - we just want to make sure to clear it so we don't give it to the wrong user. I don't think this is physical-access-to-the-hard-drive-sensitive data.