message: Cleanup string usage
diff: @@ -37,13 +37,18 @@ using namespace caf::net;
  namespace {
  +// TODO: switch to std::operator""s when switching to C++14
  +std::string operator"" _s(const char* str, size_t size) {
  + return std::string(str, size);
  +}
  +
  struct fixture : test_coordinator_fixture<>, host_fixture {
  fixture() {
  mpx = std::make_shared<multiplexer>();
  if (auto err = mpx->init())
  CAF_FAIL("mpx->init failed: " << sys.render(err));
  auth.port = 0;
  - auth.host = std::string{"0.0.0.0"};
  + auth.host = "0.0.0.0"_s;
  }
  bool handle_io_event() override {
  @@ -126,7 +131,7 @@ CAF_TEST(tcp connect) {
  CAF_MESSAGE("opened acceptor on port " << port);
  uri::authority_type dst;
  dst.port = port;
  - dst.host = std::string{"localhost"};
  + dst.host = "localhost"_s;
  auto conn = make_socket_guard(unbox(make_connected_tcp_stream_socket(dst)));
  auto accepted = make_socket_guard(unbox(accept(acceptor)));
  CAF_MESSAGE("accepted connection");
  @@ -145,7 +150,7 @@ CAF_TEST(doorman accept) {
  CAF_MESSAGE("connecting to doorman");
  uri::authority_type dst;
  dst.port = port;
  - dst.host = std::string{"localhost"};
  + dst.host = "localhost"_s;
  auto conn = make_socket_guard(unbox(make_connected_tcp_stream_socket(dst)));
  CAF_MESSAGE("waiting for connection");
  while (mpx->num_socket_managers() != before + 1)
  