Mass class renaming: s/syslog-ng/syslogng/

Recent puppet complains about hypens in class names.
Let's rename the whole module as "syslogng".

Signed-off-by: Luca Bruno <luca.bruno@rocket-internet.de>
Merge pull request #1 from lucab/master

Mass class renaming: s/syslog-ng/syslogng/