"Report another bug" text for package bug pages contains a lowercase distro name

[Graham Binns]

Looking at bugs web page like bug 213908 at the bottom of the page it says:

    * Report another bug about apt in ubuntu
    * List open bugs for apt in ubuntu

Both of these have the word Ubuntu in lowercase but it should probably be in uppercase.

What's being output here is the target DistributionSourcePackage's displayname (context/target/displayname). This is a @property that returns `"%s in %s" % (self.sourcepackagename.name, self.distribution.name).

Since the displayname property is for displaying, there's no reason not to alter this to use displaynames where appropriate.

[William Grant (wgrant)]

    @property
    def displayname(self):
        """See `IDistributionSourcePackage`."""
        return '%s in %s' % (
            self.sourcepackagename.name, self.distribution.displayname)