man: rename systemd.conf to systemd-system.conf

Alias as systemd-user.conf is also provided. This should help
users running systemd in session mode.

https://bugzilla.redhat.com/show_bug.cgi?id=690868
sysctl: fix uninitalized memory access in error path

src/sysctl/sysctl.c: In function ‘parse_file’:
src/sysctl/sysctl.c:172:41: warning: ‘property’ may be used uninitialized in this function [-Wmaybe-uninitialized]
log_error() if inotify_add_watch() fails

[zj: Reworded message s/to watch/to add watch on/ to make it clear
     that it was the watch init action that failed, and not the
     "process of watching". I think this way it'll be clearer to
     people who don't know what inotify does.]