Firehose enhancements

Bunch of improvements to the firehose stanza, including style fixes, improved SQL queries, working pagination with RSM plus JDBC tests.

It also allows /firehose to return items from all nodes, which is interesting for a multi-domain setup. The logic of this method will change when we address https://github.com/buddycloud/buddycloud-server-java/issues/234 though.
actually we already have those