first partially working parts of persisted dynamic input model
use jersey2 via netty for REST API

implement Metrics filters for jersey2
use Jersey 2 injection for access to Core.class in rest resources
fixed path for test
this needs the currently unreleased org.graylog2:jersey-netty module (also on github)
fix merge problems after updating to jersey-netty
use the injected Core reference
remove explicit ObjectMapper instances, use the super class's instance
merge with InputsResource change
remove per-resource prettyPrint parameter, now handled by RestResource centrally

if you use RestResource.json() it automatically detects the optional pretty=true parameter
working version of plugin configuration requests
improve response structure of input configurations