Modifying the start command for the web-interface in SOURCES/init.d-graylog2-web-interface.

Instead of using /opt/graylog2-web-interface/lib/* as the classpath I'm using the example provided by
the ./bin/graylog2-web-interface script that comes with the raw release of the web-interface and specifying
all JAR files in the class path individually.

I originally tried to work around this but due to issues that arose after some browser cache clearing and updates
I had trouble loading CSS and JS assets, opened https://github.com/Graylog2/graylog2-web-interface/issues/326 as a result.

Will close that issue when pushed to github.