fix(sys-apps/systemd) pick in upstream systemd bugfixes

Also add the --root= files from @marineam and me so that our initramfs
scripts will work properly in the near future.
clean(sys-apps/systemd) remove unused systemd patches

These are no longer used by any ebuild, so drop them to clean things up
clean(sys-apps/systemd) remove unused 207 systemd ebuild
feat(sys-apps/systemd) add support for multiple dns servers

As requested by @polvi
Merge pull request #432 from gregkh/systemd

sys-apps/systemd : lots of bugfixes and multiple dns server feature