Upgrade 1.2.0 to 1.2.1 blocking start of `maxscale` service

If `maxscale` being upgraded from existing 1.2.0 environment to 1.2.1, service stops booting up at all.

It's not creating any useful logs, just "service failed to start" and "MaxScale is shut down." in logs every time you try to start service.
I spent some time together with kolbe on IRC (thanks!) on trying to figure out what's happened.

It appears, that:

1. 1.2.0 had a bug in init-script (https://mariadb.atlassian.net/browse/MXS-374), because of it maxscale started under root, not under 'maxscale' user
2. installed maxscale 1.2.0 created all files with root rights
3. then 1.2.1 came out, fixed bug in init-script
4. several previously existed files and paths are still owned by root, blocking `maxscale` start

It could be a good idea to add those commands to init-script:

chown -R maxscale:maxscale /var/lib/maxscale/

or

chown maxscale:maxscale /var/lib/maxscale/.secrets

chown maxscale:maxscale /var/lib/maxscale/readconn.sock

chown maxscale:maxscale /var/lib/maxscale/errmsg.sys

chown -R maxscale:maxscale /var/lib/maxscale/data/