[meta] Application.* API will be removed

[Infocatcher]

See https://bugzilla.mozilla.org/show_bug.cgi?id=1090880

• [x] Bookmarks Folder
  Application.prefs.getValue()/setValue()
Application.name
• [x] Custom Buttons Editor: Toggle on Top
  Application.storage.get()/set()
• [x] Source Editor
  Application.storage.get()/set()
• [x] Cookies Permissions
  Application.storage.get()/set()
• [x] Extensions Developer Tools
  Application.restart()
Application.quit()
• [x] Extensions Installer
  Application.restart()
• [x] Toggle Flash
  Application.prefs.getValue()
• [x] Toggle Restartless Add-ons
  Application.prefs.getValue()