Changes to support stream rule editor

Allowing to fetch/update single stream rules
Proper serialisation of single stream rules
Allowing instantiation of stream router for stream rule matching tests
Introducing parameter for stream router to en/disable caching
fix default ports for gelf, syslog and raw inputs. fixes #336
Merge branch '020' of github.com:Graylog2/graylog2-server into 020
Merge remote-tracking branch 'upstream/020' into 020