Make mediawiki::jobrunner not include ::mediawiki

We can't include ::mediawiki on osmium, because its spidering dependencies
include things that won't work on Trusty, either because they require packages
that aren't available (wikimedia-task-appserver) or because they depend on
legacy configurations that aren't in puppet (like the existence of /a/common).
So make mediawiki::jobrunner not include mediawiki, and instead express the
dependency by including it from role::applicationserver. This makes
mediawiki::jobrunner usable on osmium, where it will provision the job runner
init scripts.

Change-Id: I1ff793a96eb63776744899f6b7753c24c1959c20