Per discussion with Brent, allow empty MAC (for now).
Per discussion with Brent, allow empty MAC (for now).

If we don't allow an empty MAC address, things like the msfconsole 'hosts' command don't work and some of the existing rspec tests start failing.

I verified this change will still catch invalid MAC addresses the user provides.

bcook-r7/metasploit_data_models,rapid7/metasploit_data_models,rapid7/metasploit_data_models,bcook-r7/metasploit_data_models,rapid7/metasploit_data_models,bcook-r7/metasploit_data_models