1. Test JARs are built & published
1. log4j.resources is explicitly excluded. Without this, downstream test run logging depends on the order the JARs are listed/loaded
1. sql/hive pulls in spark-sql &...spark-catalyst for its test runs
1. The copied in test classes were rm'd, and a test edited to remove its now duplicate assert method
1. Spark streaming is now build with the same plugin/phase as the rest, but its shade plugin declaration is kept in (so different from the rest of the test plugins). Due to (#2), this means the test JAR no longer includes its log4j file.

Outstanding issues:
* should the JARs be shaded? `spark-streaming-test.jar` does, but given these are test jars for developers only, especially in the same spark source tree, it's hard to justify.
* `maven-jar-plugin` v 2.6 was explicitly selected; without this the apache-1.4 parent template JAR version (2.4) chosen.
* Are there any other resources to exclude?

Author: Steve Loughran <stevel@hortonworks.com>

Closes #5119 from steveloughran/stevel/patches/SPARK-6433-test-jars and squashes the following commits:

81ceb01 [Steve Loughran] SPARK-6433 add a clearer comment explaining what the plugin is doing & why
a6dca33 [Steve Loughran] SPARK-6433 : pull configuration section form archive plugin
c2b5f89 [Steve Loughran] SPARK-6433 omit "jar" goal from jar plugin
fdac51b [Steve Loughran] SPARK-6433 -002; indentation & delegate plugin version to parent
650f442 [Steve Loughran] SPARK-6433 patch 001: test JARs are built; sql/hive pulls in spark-sql & spark-catalyst for its test runs