Exclude more artifacts which are dependencies of hadoop-* modules,
with the goal of keeping conflict out of downstream applications.
In particular we have pruned the dependencies of of:
-zookeeper
-other libraries referencing logging
This keeps slf4j-log4j12 and log4j12 off the classpath
of applications importing hadoop-common.
Somehow logback references do still surface; applications
pulling in hadoop-common directly or indirectly should
review their imports carefully.
Contributed by Steve Loughran
a0ce2170db