Add Fish Hook to PlayerFishEvent [#Bukkit-1025]

This patch adds a reference to the Fish entity (ie. bobber/hook) to the PlayerFishEvent.  This allows plugins to determine its location after casting as well as simulate bites.

Bukkit PR: 
https://github.com/Bukkit/Bukkit/pull/781

Ticket:
https://bukkit.atlassian.net/browse/BUKKIT-1025