move WSAStartup to init

WSAStartup should be called before using any other socket
functions. BindListenPort is not called if not listening.

Closes #2585.
Merge pull request #2586 from laanwj/2013_04_winsock_init

move WSAStartup to init
Try to increase file descriptor rlimit if necessary

As the default can be too low, especially on OSX.