Merging the functionality of the original init.d-graylog2-server script with https://gist.github.com/corey-hammerton/7146915

The new script removes the use of nohup and runs the command as a separate user in the background. This
is the primary change.
Adding a short java validation block in init.d-graylog2-server.

This functionality will determine if a JAVA path exists and is executable. If both criteria fail
the script fails
Moving the CMD variable declaration to the beginning of the script init.d-graylog2-server
Configuring the script init.d-graylog2-web-interface to the status similar to the current settings of init.d-graylog2-server.

Removing the use of nohup and replacing it with running the start command as a custom user.

Standardizing the start, stop, get_pid and pid_running functions
Removing the GRAYLOG2_PID variable from sysconfig-graylog2-web-interface

The web-interface maintains it's own PID file under /opt/graylog2-web-interface/RUNNING_PID, having
this variable declared in sysconfig-graylog2-web-interface will cause almost all valid functions of
init.d-graylog2-web-interface to stop.

Adding some whitespace around functions in init.d-graylog2-web-interface and an echo after the start
if block to allow the echo_success function to properly display the OK string