Updates to zipkin-java 0.4.1, particularly docker images

Zipkin 0.4.1 obviates some duplication of configuration. It is also the
first version that's published as a docker image.

By switching to the published image of zipkin-java, we can be more
consistent, as `spring-cloud-sleuth-zipkin-stream` is derived from that,
not the scala query service.

spring-cloud-sleuth-samples/spring-cloud-sleuth-sample-zipkin-stream/src/main/resources/application.yml

@@ -7,14 +7,6 @@ spring:
   datasource:
     initialize: false
 
-zipkin:
-  collector:
-    sample-rate: 1.0 # percentage to traces to retain
-  query:
-    lookback: 86400000 # 7 days in millis
-  store:
-    type: mem # default is inMemory
-
 ---
 spring:
   profiles: mysql
@@ -30,4 +22,4 @@ spring:
     enabled: false
 zipkin:
   store:
-    type: mysql # default is inMemory
+    type: mysql # default is mem (in-memory)