refactor loading throughput data

per node goes to Node.class
per cluster goes to ClusterService
de-statize field names loading

moved to MessagesService, which deals with interacting with messages and their metadata. have it injected to gain access to its functionality
update copyright on all java files

don't do it in templates, because it screws everything up.
Merge git://github.com/Graylog2/graylog2-web-interface into develop