[C] Call WorldSaveEvent when worlds are saved. Fixes BUKKIT-3681

**The Issue:**
WorldSaveEvent should always be called when a world is saved, but it isn't.

**PR Breakdown:**
This change makes net.minecraft.server.WorldServer call a WorldSaveEvent (instantiated with argument this.getWorld()) everytime the save-method is called.

**Testing Results and Materials:**
Tested with https://github.com/Pheasn/WorldSaveTracker and working (no duplication of the event call recognizable).
Binary for testing here: https://googledrive.com/host/0ByrehF-VA20bYUlKN1JRdU13N1U/generalbin/tracker.jar

**JIRA-Ticket:**
BUKKIT-3681 - https://bukkit.atlassian.net/browse/BUKKIT-3681