Provisioning startup scripts broken on macOS

[tresf]

Not sure what's going on, they work when QZ Tray is launched from Terminal (e.g. /Applications/QZ Tray/Contents/MacOS/QZ Tray) but not when started from other means such as automatic startup, Dock or Spotlight.

@Vzor- I don't know if there's just some wacky permissions going on trying to write to the Desktop folder from a subprocess? If that's the case, we can probably adjust our tests to write somewhere else. What's weird is we write our "Zip Logs to Desktop" there but maybe the subprocess interferes with those permissions.

To reproduce:

1. ant pkgbuild -Dprovision.file=/Users/owner/tray/test/qz/installer/provision/resources/provision.json
2. Install

Notice that this portion of the code didn't run properly:

tray/test/qz/installer/provision/resources/script2

Line 8 in c78e35a

echo "$date Successful provisioning test from '$shell': $script" >> "$user/Desktop/provision.log"

tray/test/qz/installer/provision/resources/script3.sh

Line 6 in c78e35a

echo "$date Successful provisioning test from '$shell': $script" >> "$user/Desktop/provision.log"