Merge pull request #357 in ZP/z-push from bugfix/ZP-1039-z-push-admin-returns-exit-code-0 to develop

* commit '102507ff':
  ZP-1039 Don't use die() to terminate in error case for gab-sync.
  ZP-1039 Don't use die() to terminate in error case for z-push-admin.

Conflicts:
	tools/gab-sync/gab-sync.php