Performance patches for graylog speeding it from 4-5k up to 50k messages from single instance

Hello Lennart,

As Konstantin (kt@odnoklassniki.ru) promised you recently, I made this pull request from our performance patches. We patched both graylog2-server and graylog2-plugin-interfaces (i'll make separate pull request for the former one).

Please be aware, that these patches are of performance prototype quality - i.e. it works fast, but could lack support of all use cases of your users or have some values just wired into code, where your users could want then to be configured. I believe you know your users better, so I left this part to you.

Anyway, with these patches applied, a single graylog2-server instance is serving about 50 000 syslog udp messages per second in our test environment (and < 5 000 without them). We did not tested GELF udp processing yet, so there could be more fixes there a bit later.

PS. Thos ODKL-ONLY:* commits are our local patches and not needed for you, but i cannot figure out how to drop them from pull request, sorry.