Create automatic build for Windows app

[niccokunzmann]

We can use appveyor to build the windows flappy app automatically, when a commit occurs.

[niccokunzmann]

@adarsh-ideal

Yeah, I checked that. Compiling the installer is easy and can be performed from command line, we just need the .nsi script But I need time to find an application to generate the .nsi script through command line on each new commit. - source

Why do we need a new nsi script?

[idealadarsh]

nsi is a scripting language created by NSIS to compile installers.