Fixed Fast Enumeration Bug

SPJuggler would throw exception: *** Collection <__NSArrayM:
0x1d5c8c60> was mutated while being enumerated.
2013-05-20 14:41:01.714 Catty[1252:3d07] *** Terminating app due to
uncaught exception 'NSGenericException', reason: '*** Collection
<__NSArrayM: 0x1d5c8c60> was mutated while being enumerated.'