Update JavaDocs regarding teleportation of entities. Fixes BUKKIT-4210

Up until Minecraft version 1.5 it was not possible to teleport entities
within vehicles. With the 1.5 update came the change in the Minecraft
teleportation logic to dismount before teleporting the entity, if
applicable.

This commit simply ammends the JavaDocs for the associated CraftBukkit
half regarding the action the teleportation methods will take before
completing a teleport.