Provide some documentation on how to compile watchman on Windows

This issue is related to issue #494. I would like to distribute the watchman binary along with my desktop application on Windows and Mac, which the license allows me to do. On Windows, it seems like additional DLLs are needed, which I can also distribute. However, I was wondering whether I could compile watchman with fewer dependencies so that I don't have to distribute multiple binaries for it to work on a windows system. I tried to compile watchman using cygwin, and I started getting a bunch of errors (sorry, I'm a Mac guy, I don't have a ton of experience with Windows or Cygwin) A little bit of documentation on how to compile watchman on Windows would go a long way.