remove old dependency on net-ssh moneykpatch

the ssh_login_pubkey scanner relied on functionality that
was monkeypatched into our vendored copy. this was an uneeded solution
in the first palce, and we now use a more sane method of accomplishing
the same thing

Author: David Maloney

modules/auxiliary/scanner/ssh/ssh_login_pubkey.rb

@@ -7,6 +7,8 @@
 require 'net/ssh'
 require 'metasploit/framework/login_scanner/ssh'
 require 'metasploit/framework/credential_collection'
+require 'sshkey'
+require 'net/ssh/command_stream'
 
 class MetasploitModule < Msf::Auxiliary
 
@@ -140,7 +142,7 @@ def pull_cleartext_keys(keys)
     return cleartext_keys
   end
 
-  def session_setup(result, ssh_socket)
+  def session_setup(result, ssh_socket, fingerprint)
     return unless ssh_socket
 
     # Create a new session from the socket
@@ -157,7 +159,7 @@ def session_setup(result, ssh_socket)
       'KEY_PATH'        => nil
     }
 
-    info = "SSH #{result.credential.public}:#{ssh_socket.auth_info[:pubkey_id]} (#{ip}:#{rport})"
+    info = "SSH #{result.credential.public}:#{fingerprint} (#{ip}:#{rport})"
     s = start_session(self, info, merge_me, false, conn.lsock)
     self.sockets.delete(ssh_socket.transport.socket)
 
@@ -229,7 +231,9 @@ def run_host(ip)
           credential_core = create_credential(credential_data)
           credential_data[:core] = credential_core
           create_credential_login(credential_data)
-          session_setup(result, scanner.ssh_socket)
+          tmp_key = result.credential.private
+          ssh_key = SSHKey.new tmp_key
+          session_setup(result, scanner.ssh_socket, ssh_key.fingerprint)
           :next_user
         when Metasploit::Model::Login::Status::UNABLE_TO_CONNECT
           if datastore['VERBOSE']