Authenticode Sign qz-tray.exe, uninstall.exe

[tresf]

I thought I had an open item for this... but apparently not...
We need to sign all exe's that we distribute. Partial support was written in #535 but it was closed as wontfix since the patch wasn't effective and the changes didn't address the uninstaller.

• Sign the qz-tray.exe
• Sign the uninstall.exe

Since ant doesn't handle blank values well we have target-specific logic to handle authenticode. I feel this code will become redundant when signing three separate files so I'm asking @bberenz to help write a reusable ant target for this. :D

[tresf]

I'm asking @bberenz to help write a reusable ant target for this. :D

Reusable ant targets done via #614.

the patch wasn't effective and the changes didn't address the uninstaller.

As it turns out, the uninstall.exe cannot be signed because it's created and bundled into the installer by makensis and workarounds provided by NSIS aren't compatible with Linux or MacOS. New workaround published and available in #614.