Apport 2.5: Better support for third-party and PPA packages

I just released Apport 2.5 with a bunch of new features and some bug fixes.

By default you cannot report bugs and crashes to packages from PPAs, as they are not Ubuntu packages. Some packages like Unity or UbuntuOne define their own crash database which reports bugs against the project instead. This has been a bit cumbersome in the past, as these packages needed to ship a /etc/apport/crashdb.conf.d/ snippet. This has become much easier, package hooks can define a new crash database directly now (#551330):

def add_info(report, ui):
   if determine_whether_to_report_to_upstream:
       report['CrashDB'] = '{ "impl": "launchpad", "project": "picsaw" }'

(Documented in package-hooks.txt)

Apport now also looks for package hooks in /opt (#1020503) if the executable path or a file in the package is somewhere below /opt (it tries all intermediate directories).

With these two, we should have much better support for filing bugs against ARB packages.

This version also finally drops the usage of gksu and moves to PolicyKit. Now we only have one package left in the default install (update-notifier) which uses it. Almost there!