update app file to match the official

This fixes an error when you use the default amqp_client config

(ubic@127.0.0.1)3> {ok, Connection} = amqp_connection:start(#amqp_params_network{}).

=ERROR REPORT==== 11-Feb-2013::16:03:31 ===
** Generic server <0.293.0> terminating 
** Last message in was connect
** When Server state == {state,amqp_network_connection,
                            {state,undefined,undefined,undefined,undefined,
                                undefined,false},
                            <0.292.0>,undefined,
                            {amqp_params_network,<<"guest">>,<<"guest">>,
                                <<"/">>,"localhost",5672,0,0,0,infinity,none,
                                [#Fun<amqp_auth_mechanisms.plain.3>,
                                 #Fun<amqp_auth_mechanisms.amqplain.3>],
                                [],[]},
                            undefined,undefined,
                            #Fun<amqp_connection_sup.0.55585968>,
                            #Fun<amqp_connection_sup.2.55585968>,false}
** Reason for termination == 
** {{case_clause,undefined},
    [{amqp_network_connection,inet_address_preference,0,
                              [{file,"src/amqp_network_connection.erl"},
                               {line,154}]},
     {amqp_network_connection,gethostaddr,1,
                              [{file,"src/amqp_network_connection.erl"},
                               {line,161}]},
     {amqp_network_connection,connect,4,
                              [{file,"src/amqp_network_connection.erl"},
                               {line,110}]},
     {amqp_gen_connection,handle_call,3,
                          [{file,"src/amqp_gen_connection.erl"},{line,177}]},
     {gen_server,handle_msg,5,[{file,"gen_server.erl"},{line,588}]},
     {proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,227}]}]}