httpd version signature patch

[Martin]

Hi,

here is patch for version signature enable/disable (from our todo list). 
Possible syntax:

  set httpd port 2812 and
    ...
    [signature [enable|disable] ]

or

    [[enable|disable] signature]


By default is the signature enabled if the option is omited. I'm currently in 
the school and don't have cvs access, so i will add documentation for it to 
monit.pod in the afternoon. If you agree, i can commit it.


Cheers,
Martin