xbmc: cleanup
systemd: move /etc/systemd/system to /storage/.config/system.d

this fixes systemctl enable/disable/is-enabled/list-units/...
xbmc: prepare to migrate service addons to systemd
vdr-addon: convert to systemd service
vdr-addon: ups. accidently changed loglevel in previous commit
projects/ARCTIC_MC: disable oem support. remove oem/ARCTIC_MC
tvheadend: convert to systemd service
minor cleanup
vdr & tvheadend: forgot to rework WAIT_FOR_FEINIT
xbmc: install systemd-addon-wrapper in correct location

ups ;)
xbmc: service addons/systemd: also handle addon updates
new package: re-add 'unzip'

closes #2820
boblightd: convert to systemd service
ffmpeg: add xbmc patch
xbmc: update to xbmc-13.alpha-ca8ade7
remove 'openelec' user

.. as it does not make sense and causes lot of confusion
Merge pull request #2822 from stefansaraev/booo

remove 'openelec' user