Based on fluentd-kubernetes-daemonset but with multiple plugins.
On new releases by upstream update the submodule and then check for differences
between plugins with ./checkdiff.bash.
Symlink common files into place with dosymlink.bash.
Build a common gemfile that includes all plugins with buildgemfile.bash and
then bundle to update the Gemfile.lock.
Then, manually combine the conf/fluent.conf files as desired.
Finally, run the ./publish.bash to push the image to docker hub.