* fix unit name: the unit name on Ubuntu is `redis-server.service`
* services which need a working redis require both After= and Wants=
See the description in the `systemd.unit` man page.
yq package is now provided in the BigBlueButton support PPA for BBB 2.5,
so we can depend on the package now. Ensure the dependency is specific
to avoid an incompatible yq version 4 from being installed.
Remaining, to be handles separately:
bbb-html5 before-remove and after-install -- sip.nginx needs to be
handled in bbb-conf
bbb-freeswitch-core -- /tmp/vars xml, etc. -- not sure how to handle
