Changing appImage fails

[jg00dman]

We need to check for exec bit permission before copying the new appimage into place. If this isn't set running will fail of course.

We also need to update the config file after copying the new app image into place. Or the old one is still used.

And possibly we need to offer to clean out old appImages?

[thw26]

If we clean out old AppImages, we'd probably want to keep at least two so that a user can revert to the previous image.

[thw26]

Superseded by #422