Document release date of 0.9.10
The syslog-ng script should restore /dev/xconsole permissions because that's what the official init script does
Fix syslog-ng.

The system() source in the default syslog-ng config file does
not work in Docker because it tries to access /proc/kmsg,
which is not allowed due to Docker's privileges. We replace
it by a source that only reads from /dev/log.