Update build instructions for windows
Update build instructions for windows

* Note about VS2013 to avoid Qt issues
* Note about NSIS for package creation

JoshChristie/displaz,rotorliu/displaz,rotorliu/displaz,JoshChristie/displaz,rotorliu/displaz,rotorliu/displaz,JoshChristie/displaz,JoshChristie/displaz,JoshChristie/displaz