FIX: Properly close spectacle after Save As

Summary: BUG: 389694

Test Plan:
  # run Spectacle via shell
  # Have Quit after Save or Copy checked.
  # Hit Save As and save the image
  # Spectacle closes

Reviewers: davidre

Reviewed By: davidre

Subscribers: broulik, #spectacle

Tags: #spectacle

Differential Revision: https://phabricator.kde.org/D23534