Windows support added

Hi jl777, I mentioned via pm from gmoneycoin at bitcointalk that I'd send you the Windows code changes. 

Modifications to the code are made with ifdefs using _WIN32 definition and also changing sleep to sleepOS, usleep to usleepOS, and close to CloseSocket.

I'm no expert at github, but you can follow these instructions to merge a pull request:
https://help.github.com/articles/merging-a-pull-request