TISTUD-1952 Automate the process of signing Mac binaries for Gatekeeper
      - Sign the app before we generate a DMG.
      - The underlying zip on the new build setup won't contain a signed version. Ideally we'd run a post build action off the rcp build on a mac node to do this in the original zip.
      - otherwise we need to use this signed zip when we sync instead of the original