Removing all instances where the LOG_FILE variable is declared/used

With the new log4j configuration files there is no console
writing running in java so there is no need for file redirection
at the command-line level.

Removing the lines containing the LOG_FILE variable in
sysconfig-graylog2-server and sysconfig-graylog2-web-interface.

Removing the LOG_FILE declaration and hard-coding a hard stdout
redirection to /dev/null in init.d-graylog2-server and
init.d-graylog2-web-interface