Unload lorcon modules

None of the lorcon / lorcon2 modules have been functional for a long
time, due to the lack of a "Lorcon" gem. It's unclear where it went.

I'm happy to include it and get these working again, but until someone
comes up with some functional code (hint: 'gem install' doesn't work) I
don't see any reason to keep shipping these.

Is there some trick people are doing to make these work? As far as I can
see, they are broken by default.

````
msf auxiliary(wifun) > show options

Module options (auxiliary/dos/wifi/wifun):

   Name       Current Setting  Required  Description
   ----       ---------------  --------  -----------
   CHANNEL    11               yes       The initial channel
   DRIVER     autodetect       yes       The name of the wireless driver
for lorcon
   INTERFACE  wlan0            yes       The name of the wireless
interface

msf auxiliary(wifun) > run

[*] The Lorcon2 module is not available: cannot load such file --
Lorcon2
[-] Auxiliary failed: RuntimeError Lorcon2 not available
[-] Call stack:
[-]
/home/todb/git/rapid7/metasploit-framework/lib/msf/core/exploit/lorcon2.rb:67:in
`open_wifi'
[-]
/home/todb/git/rapid7/metasploit-framework/modules/auxiliary/dos/wifi/wifun.rb:29:in
`run'
[*] Auxiliary module execution completed
````

If there *is* a way to use these, then please say so... @mubix might know, he keeps a lot of weird unofficial lore about how to get old Metasploit stuff working. @rsmudge might know something, too. If people are relying on them being there, we can see about bringing them back to life (or at least, slap a deprecation warning on them).