Fix test failure against Twisted 14.0.0 (and likely earlier).

Start the factory before trying to use it.  This is how factories are actually driven.

Also change the literal log string the test asserts against.  The formatting code is in
Twisted and Twisted decided to change the specific way the formatting was done.  Too bad,
Nevow.
Merge pull request #30 from exarkun/nativeize-29

Fix test failure against Twisted 14.0.0 (and likely earlier).