[update] update to upstream 1.6.28
Squashed 'dbus/' changes from d5685bc..c79b6e0

c79b6e0 1.6.28
d1ab585 Revert "config: change default auth_timeout to 5 seconds"
39f4b36 Log to syslog when auth_timeout drops an incomplete connection
97adc57 1.6.27

git-subtree-dir: dbus
git-subtree-split: c79b6e09d14912dc489f4fc3469338c87d7abb44
Merge commit '206fe0e9fd28c90a265333786cd360ec57b189c8'
[update] update spec version to 1.6.28