[B] Call WorldSaveEvent on SaveCommand. Fixes BUKKIT-3681

**The Issue:**

When the "save-all" command is used, the WorldSaveEvent is not triggered, so plugins relying on the event don't save their data (or do something else).

**Justification:**

The event is always called when saving worlds, but not when saving is forced by a SaveCommand. There is no reasonable explanation for this to me.

**PR Breakdown:**
This PR triggers a WorldSaveEvent for every world that is saved by the org.bukkit.command.defaults.SaveCommand class.

**Testing Results and Materials:**
I found no duplication of the event implementation. I used this plugin for testing: https://github.com/Pheasn/WorldSaveTracker .
Binary can be found here: https://googledrive.com/host/0ByrehF-VA20bYUlKN1JRdU13N1U/generalbin/tracker.jar

**JIRA Ticket:**
BUKKIT-3681 - https://bukkit.atlassian.net/browse/BUKKIT-3681