make ftp guest attempts optional

modules/auxiliary/scanner/ftp/ftp_login.rb

@@ -126,9 +126,11 @@ class Metasploit3 < Msf::Auxiliary
   # Always check for anonymous access by pretending to be a browser.
   def anonymous_creds
     anon_creds = [ ]
+    if datastore['RECORD_GUEST']
       ['IEUser@', 'User@', 'mozilla@example.com', 'chrome@example.com' ].each do |password|
         anon_creds << Metasploit::Framework::Credential.new(public: 'anonymous', private: password)
       end
+    end
     anon_creds
   end