abrtd.service: Don't order after syslog.target

http://www.freedesktop.org/wiki/Software/systemd/syslog/
https://fedorahosted.org/fpc/ticket/177#comment:2
http://lists.opensuse.org/archive/opensuse-packaging/2013-05/msg00102.html
Merge pull request #793 from scop/master

abrtd.service: Don't order after syslog.target