Update 3.6.0r1 --> 3.6.0r2

• enabled JSON by default (it's getting popular, and syslog-ng complains at startup if unavailable)
• added scl.conf to default config
• enabled the system() source by default (which handles differences automagically among different platforms and releases)

Submitted by: Peter Czanik <peter.czanik@balabit.com> (syslog-ng upline)