README.md: strip trailing whitespace

Signed-off-by: Michael Ira Krufky <mkrufky@linuxtv.org>
serve: fix build on osx mavericks: error: cannot create a non-constant pointer to member function

serve.cpp:1595:69: error: cannot create a non-constant pointer to member function
                                ret = server->feed_servers[portnum].start_udp_listener(portnum, server->add_feeder, server);
                                                                                                ^~~~~~~~~~~~~~~~~~
serve.cpp:1598:69: error: cannot create a non-constant pointer to member function
                                ret = server->feed_servers[portnum].start_tcp_listener(portnum, server->add_feeder, server);
                                                                                                ^~~~~~~~~~~~~~~~~~

Signed-off-by: Michael Ira Krufky <mkrufky@linuxtv.org>