Redirecting all stdout output to /dev/null in both init scripts

Modifying the ending of the start command in init.d-graylog2-server
and init.d-graylog2-web-interface that redirects all stdout
traffic to /dev/null and also redirects all stderr traffic to
stdout.

Since the new log4j configurations are successfully implemented
for both services they do not output to stdout, unless configured,
so log file redirection is not needed.