better support for transactions and doing commit() via the database object returned
Some things set just ACCEPT rather than HTTP_ACCEPT
added a 'one of' condition
JSON doesn't allow NaN, so we'll just block it here.
Write out responses in Python3 as strings
Adding newline after request line in request dump.

Writing dump files as utf-8.
Converting datetime into ISO format rather than unixtime, it's got much more
useful information, like timezone and fractions of seconds.
This was a nice idea, but didn't work well.