Move graylog2-server configration files to /etc/graylog2
Add preinst and postrm scripts for graylog2-server
Run `bundle package` after `bundle install` in graylog2-web and remove custom patch
Small changes to graylog2-server Debian init script
Move `bundle install` (from cache) to postinst phase of graylog2-web
Generate secret token in postinst script of graylog2-web