Eliminating of object pool concept from AutoPacketFactory

The use of an object pool complicates AutoPacket's lifetime and does not appear to improve performance.  AutoPacket is actually a very small type; rather than using a pool to optimize initialization, it's probably more worthwhile to investigate memoization of the constructor into the AutoPacketFactory type.
Merge pull request #254 from leapmotion/ref-factorypool

Eliminate of object pool concept from AutoPacketFactory