[Fixed] name of spawn and despawn tasks in encounter.
[Fixed] finishing of spawn and despawn tasks in encounter.
[Fixed] call to despawn function in old man encounter.
[Added] isEncounterFinished function to the old man encounter.
[Added] Sith Shadow encounter.
[Added] linking of old man encounter and sith shadown encounter.
[Added] nil protection in a few functions.

Change-Id: Id00a6ff1da7acece57591bbe8e2952c4ed27e193