Merge pull request #564 in ZP/z-push from feature/ZP-1165-tools-z-push-admin-could-have-an to develop

* commit 'b8c4b3e9':
  ZP-1165 Remove device command honours --days-old parameter.
  ZP-1165 Added days-ago as an alias for days-old option.
  ZP-1165 Added days-old option for lastsync action.