v.2.8.1 hotfix self-update

• Fixed the in-app self-update looping forever on a fresh update: a stray extra slash in the
  extraction path meant a .vpk-packaged update (as opposed to the old PSARC format) got written
  somewhere other than where the app actually loads from, so it kept detecting itself as outdated
  and re-downloading the same update every time it relaunched. If you're stuck in this loop on
  v.2.8.0, install this version's .vpk manually once to break out of it.