Better update failure handling

[ron-popov]

The current situation is that if the download of one of the files fails, then it deletes all of the files.
I think a better solution would be to save the new files in a temp "folder", lets call it SkyX/temp/.
Once all of the files finished downloading, we will copy all of the files from SkyX/temp/ to SkyX/ and the user will be prompted to reload Geo-FS.

I think this method will make it easier for users with an unreliable internet connection, because one fail would delete SkyX entirely.