Fix FDWatcher on Windows

With this and https://github.com/JuliaLang/ZMQ.jl/pull/28 I am able to use IJulia on Windows with the latest binary d32bc80 on the download page (thank you, Jameson!), after removing sys.ji and regenerating.

![image](https://f.cloud.github.com/assets/327706/1144838/4b004878-1dd3-11e3-883b-0c1e471ac412.png)

Manual steps:
- install anaconda
- compiled ZMQ lib using mingw64; copied libzmq.dll to julia/bin
- RPMmd.update(); RPMmd.install("nettle")
- start "ipython qtconsole --profile julia" from *inside* of Julia because of https://github.com/JuliaLang/julia/pull/4252

@loladiro @vtjnash @stevengj