Sign the Windows executable to avoid Win 10 SmartScreen Blocking

[tofi86]

We have a user reporting that the EPUB-Checker app gets blocked by Windows Defender SmartScreen on Windows 10 because the executable is not signed:

https://twitter.com/MartinGreenhill/status/1153668391313530883

Signing the Windows EXE requires a certificate and a build process on Windows or on Linux. It doesn't seem to be supported on Mac, which is a problem because in order to build a valid signed Mac App the build process must run on a Mac.

At the moment we don't have a solution for this problem.

[tofi86]

A user on the launch4j forum points to a maven plugin for cross platform code signing: https://sourceforge.net/p/launch4j/bugs/192/