Release v2.1.7

Release v2.1.6

Need public static access to the `BaseServerStartup.defaultChannelCon…

…fig()` method for some unit-tests

remove ZuulNettyReqRespTransformer

Add a metric to track unresolved DNS hosts

minor cleanup of filter loading

Merge branch '2.1' of https://github.com/Netflix/zuul into 2.1

remove modules from build

Merge pull request Netflix#305 from ServiceArchitecture/zuulfilter-ad…

…d-trace-monitor

Add MonitoringHelper.initMocks() to ZuulFilter TestUnit, otherwise it…