Code review comment for lp:~leonardr/launchpadlib/trusted-workflow

This branch introduces a generic engine for a trusted request-token-authorization client. I'm doing this because by and large, third-party developers aren't satisfied with opening the user's web browser and having them authorize a request token through the browser. They want a client that fits in with the rest of the UI. This generic engine can be used by command-line and GUI clients, and I've tested it by writing a scriptable client that implements stubs for all the plugin methods.

I have not written all the tests I'm going to write for this client, but I've written a representative sample, and I want to get what I have landed because this branch is getting kind of large.

There are two unrelated changes in this branch that I should have caught in my earlier branch (json-token-format):

1. I added launchpadlib/apps.py, which was written for the previous branch but I forgot to bzr add it. This contains the class tested by doc/command-line.txt.

2. A test in browser.txt was failing because of a bug in Launchpad. I filed a bug, hacked the test, and added a XXX.