The default CONVOY_ROOT value in convoy.wsgi is no longer correct.

Problem: In a newly set-up Launchpad development environment, HTTPS requests that utilize `convoy`, such as when a page tries to access "https://bugs.launchpad.test/+combo/?yui/yui/yui-min.js&lp/meta.js&yui/loader/loader-min.js", result in a "400 bad request" response from the test instance.

Apparent Cause: According to the Launchpad mailing list, the TLD of the various domain names used in the Launchpad development environments changed from ".dev" to ".test" (e.g. "launchpad.dev" became "launchpad.test"). When setting up a development environment, Launchpad utilizes a custom branch of `convoy` that contains a `convoy.wsgi` file. The default value for `CONVOY_ROOT` contained in that file has not been updated to reflect the recent change in the TLD.

Apparent Solution: Changing the default `CONVOY_ROOT` value in `convoy.wsgi` from "/srv/launchpad.dev/convoy" to "/srv/launchpad.test/convoy" fixes the problem (in my development environment, at least). I have created a personal branch from the Launchpad-specific `lp:~launchpad/convoy/packaging` and modified it to incorporate the fix. For now, my personal branch has just been pushed to `lp:~zriv/+junk/convoy_root_fix`.

Hopefully I have provided enough information concerning this issue to be helpful, but I am very new to the Launchpad code base. If I have gotten anything wrong, you would like me to provide more information, or I need to perform any further steps, please just let me know. Thank you.