Add info when no packages are 'available'

[jskladan]

The GUI should inform the user when no packages are not added to the 'list' (or to be precise none are put into the bodhi_worker queue). This might be caused by several possibilities (as the code is now)

packagesworker.py

    def load_installed(self, releasever):
            ...
            if installed_timedelta < installed_max_days:
                if rel.startswith('fc') and releasever in rel:
                    if pkg.ui_from_repo == '@updates-testing':
                        self.bodhi_workers_queue.put(pkg)
                        print "putting to queue", pkg

1. no packages were installed in the last installed_max_days days
2. no packages from the selected release are installed
3. no packages from @updates-testing are installed

I'd suggest altering the logic a bit (pseudocode):

    def load_installed(self, releasever):
        ...
        _updates_testing = False
        _max_days = False
        _releasever = False
        ...
            if pkg.ui_from_repo == '@updates-testing':
                _update_testing = True
                installed_timedelta = now - installed
                if installed_timedelta < installed_max_days:
                    _max_days = True
                    if rel.startswith('fc') and releasever in rel:
                        _releasever = True
                        self.bodhi_workers_queue.put(pkg)
                        print "putting to queue", pkg

So we can inform user via GUI, that no packages are shown since

1. he has no packages from @updates-testing installed (propse a check whether updates-testing is even enabled)
2. no packages were installed in last X days
3. no packages from selected release are installed (check the actual release?)

[blaskovic]

I have idea to populate the pkg list with some text like 'No packages' and making it disabled.
I will add it soon.