Fix packaging on macOS

[ErikBjare]

Note to readers: ActivityWatch should still work on macOS, this issue is about building a stand-alone bundle not dependent on Python 3.5+ being installed on the system.

Currently PyInstaller is broken on Python 3.6, which the macOS target uses.

The relevant issue for PyInstaller is here: pyinstaller/pyinstaller#2331

A temporary workaround would be to try and make the macOS travis target use Python 3.5, but there didn't seem to be a straight forward solution.

Builds for macOS no longer required to pass in:

• activitywatch
• aw-watcher-window

Needs to be fixed for:

• activitywatch (fixed in [macos] packaging fix #45)
• aw-watcher-window (fixed in ActivityWatch/aw-watcher-window@c1b8f4c)

[ErikBjare]

I think we should just be able to grab a Python 3.5 .pkg from python.org and then install it with sudo installer -pkg /path/to/package.pkg -target /.

[ErikBjare]

Now just waiting for the travis build to pass for aw-watcher-window and then this issue is resolved.

[ErikBjare]

It passed, another job well done. Closing.