Add a quiet mode to NsTest

Right now NsTest produces an enormous log file. This may be useful for tracking down some errors. However, this can also make it hard to find the signal in the noise. It would be good to turn off the chatty diagnostics which report the result of every insert, update, delete, and select. A summary at the end may be good enough, including a summary of the number of times each kind of error (SQLState) was seen. While I'm in there, I plan to make other smallish changes.