Log Message:
2.3.0
Improvements
* New ``ResourcedToStreamDecorator`` for tracking lifecycle events of
  test resources, and possibly integrate with subunit.
* Make ``KeysEqual`` usable with no arguments, i.e. match a dict with
  no keys.
* Add ``testtools.assertions`` to the documented API modules.
* Don't add file details without content.
* Make ``testtools.twistedsupport and tests work on Python 3.