Add relevant application logs to the test result

[Allan LeSage]

In conversation with thomi, going over a test failure, the autopilot log is only so helpful without the logs from relevant apps (e.g. the camera-app in this case).

Logs on my mako are to be found under ~/.cache/upstart (although I find none for camera-app in this specific case).

[Thomi Richards (thomir-deactivatedaccount)]

To clarify some details:

If a UX test opens apps A, B, and C, then those apps log files must be added to the test result. The easiest way to do this is to call 'self.addContentUniqueName' on the test case object, passing it a name (which reflects the application being used) and a content object, as generated from autopilot.content.content_from_file.