This moves to changes made in preparation of zipkin 1.0.
Here are the notables:
* Zipkin has autoconfiguration modules, where maven artifacts have the prefix 'zipkin-autoconfigure-X'
* Zipkin's ui now shares a version with everything else
* Zipkin now namespaces packages and configuration. ex zipkin.storage.X as opposed to zipkin.X
* All autoconfiguration classes are prefixed `Zipkin` to be easier to find
* Zipkin binds components like StorageComponent, as opposed to individual classes like SpanStore.
* Health checks are under the scope "zipkin" and broken down by component
* UI responsiveness is better by conditionally caching names queries for 5 minutes
* New `Collector` class, which makes logging and metrics patterns the same regardless of transport
With RxJava 1.1.4, `RxJavaPlugins.reset()` method has been made public (though `experimental`). With this update, we no longer require to manually wrapp and expose the `reset()` method of RxJavaPlugins. This PR is in conjunction with [Spring-Cloud-Netflix PR] (https://github.com/spring-cloud/spring-cloud-netflix/pull/1007) since RxJava version is maintained as a part of that dependency. Merge this PR only after the Spring-Cloud-Netflix PR is merged to avoid compile errors.
Removes wiremock as a test dependency in core (which created more
issues than you might expect because Tomcat and Jetty don't treay
HTTP headers in the same way apparently).
Also moves the spring-messaging dependency to where it is needed
in sleuth stream.
This important in so far that it allows us to do metrics. The actual
implementation of stream metrics is something we can work on after 1.0
if there's a time crunch.
Notably, this removes the accidental transient dependency on scala, by
removing the dependency on `zipkin-cassandra-core`. Related classes have
been vendored into `storage-cassandra`.
This also splits out `CollectorSampler` as its own thing and introduces
two options for instrumentation sampling:
* `BoundaryTraceIdSampler` - For high-volume sites, based on Finagle
* `CountingTraceIdSampler` - Trades lower performance for high accuracy
