Distribute updater with universal zip

[slipher]

@Viech suggested an interesting idea in #30 to distribute the updater inside the torrent/universal zip. This would let an installation originally made by the universal zip or torrent method to be updated with the updater. If we do that I guess the updater needs to filter the updater binary out of the file list.

To do this we would need to implement #90.

[DolceTriade]

Is this actually required? I'd prefer to not have a hard dependency on the updater for Unvanquished. I think if you want to use the updater/launcher, you can use it and it'll update itself.