LWS_WITH_NETWORK: cmake option for no network code

.travis.yml

CMakeLists.txt

README.md

cmake/lws_config.h.in

lib/core-net/adopt.c

lib/core-net/client.c

lib/core-net/close.c

lib/core-net/connect.c

lib/core-net/dummy-callback.c

lib/core-net/network.c

lib/core-net/output.c

lib/core-net/pollfd.c

lib/core-net/private.h

lib/core-net/server.c

lib/core-net/service.c

lib/core-net/stats.c

lib/core-net/vhost.c

lib/core-net/wsi-timeout.c

lib/core-net/wsi.c

lib/core/context.c