cappuccino/cappuccino — pull request #1551 by ggsato (2012-05-24 14:22:23+00:00)
Title: fixed shared CPDocumentController instantiation and added its test

According to *Document-Based App Programming Guide for Mac* guide, there are two ways to subclass NSDocumentController.

1. You can make an instance of your subclass in your app’s main nib file. This instance becomes the shared instance.
2. You can create an instance of your subclass in your app delegate’s applicationWillFinishLaunching: method.

I am not sure if 1 is possible, but found 2 is impossible. So I fixed CPApplication so that users can instantiate one's own subclass of CPDocumentController in applicationWillFinishLaunching.