Removed hack which ensures at least 10% of lost packets gets detected by
congestion control algorithms (through the packetDrop event).

Fixed CUBIC congestion, minimum congestion window is 2 allowing for
better packet loss detection.

Cleaned up tcp_processPacket function, separate function for processing
data and processing ACKs.
Merge pull request #197 from jdgeddes/master

Fixed TCP congestion control, no longer relies on packet drop event hack.

refs #194