More automated testing

[mboes]

From @edsko on September 24, 2012 12:59

Write a script-driven Network.Transport implementation with which we can test for specific network failures, and then use QuickCheck to generate scripts (similar to how ByteString is tested).

Copied from original issue: #38

[mboes]

From @edsko on November 6, 2012 14:42

We started to do this for Network.Transport.TCP, and it's quite aways there, but not quite done yet.