Removed port_picker and bound to port 0 in tests instead

src/node/port_picker.js

src/node/server.cc

src/node/server.js

src/node/surface_server.js

src/node/test/client_server_test.js

src/node/test/end_to_end_test.js

src/node/test/math_client_test.js

src/node/test/server_test.js