Don't use fork to start the notebook in js tests...
Don't use fork to start the notebook in js tests
It can encounter a weird segfault on OS X with sqlite when Qt is present (?!)
The main reason to use the fork was to get the port number,
but this is easy now that notebooks write a server-info file.
Further advantage is that the symptom of a failed server start
is no longer silence and hanging tests, but an actual failure with the server's log output.