Must disable dependent modules one at a time

Install og, og_vocab, views, and views_rss then try to disable all these modules. You must...

1. Uncheck og_vocab, hit Save configuration
2. Uncheck og, hit Save configuration
3. Uncheck views_rss, hit Save configuration
4. Uncheck views, hit Save configuration

We should deal with disabling modules in the same way as enabling. Let the user uncheck what he or she wants, then check if we are messing up a dependency by disabling the given module(s). If so, throw a confirm screen (just like the enable confirm screen) saying, if you want to disable og, you must also disable og_vocab, do you want to disable this module as well?