bean generator: incorrectly reports errors about missing related documents beans

To reproduce:

• start a clean project, just add the "news" and "events" features
• go to the bean writer tool, click "generate beans", and then you see a message that the beans are already up to date
• add a field to one of the doc types
• regenerate the beans

Expected: no errors/warnings in the application log and a confirmation message in the Setup app that the beans have been generated correctly

Actual: the beans are updated, but there is no confirmation message in the Setup app, and the following warning is logged (which is very strange as the feature is not installed):

INFO] [talledLocalContainer] 16.04.2015 14:44:30 WARN http-nio-8080-exec-5 [ContentBeansService.processRelatedDocuments:226] Missing related documents bean