Merge request: http://users.puzzling.org/users/mary/bzr/planet/branches/executable-tests/

[Mary Gardiner]

I've been executing the test suite under planet/tests by doing this:

$ cd [branch]
$ trial planet

trial is the Twisted test suite runner, and it finds the tests directory
and excecutes as appropriate. This has two nice features: colourful
error reporting, and no need for a custom PYTHONPATH.

This is all very nice, but it's more traditional to make the tests
directly executable. Thus, this branch.

It should apply directly after
http://users.puzzling.org/users/mary/bzr/planet/branches/original-url-tracking/

-Mary