SPARK-2798 [BUILD] Correct several small errors in Flume module pom.xml files

(EDIT) Since the scalatest issue was since resolved, this is now about a few small problems in the Flume Sink `pom.xml`

- `scalatest` is not declared as a test-scope dependency
- Its Avro version doesn't match the rest of the build
- Its Flume version is not synced with the other Flume module
- The other Flume module declares its dependency on Flume Sink slightly incorrectly, hard-coding the Scala 2.10 version
- It depends on Scala Lang directly, which it shouldn't

Author: Sean Owen <sowen@cloudera.com>

Closes #1726 from srowen/SPARK-2798 and squashes the following commits:

a46e2c6 [Sean Owen] scalatest to test scope, harmonize Avro and Flume versions, remove direct Scala dependency, fix '2.10' in Flume dependency

external/flume-sink/pom.xml

@@ -25,19 +25,20 @@
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
+  <groupId>org.apache.spark</groupId>
   <artifactId>spark-streaming-flume-sink_2.10</artifactId>
   <properties>
     <sbt.project.name>streaming-flume-sink</sbt.project.name>
   </properties>
-
   <packaging>jar</packaging>
   <name>Spark Project External Flume Sink</name>
   <url>http://spark.apache.org/</url>
+
   <dependencies>
     <dependency>
       <groupId>org.apache.flume</groupId>
       <artifactId>flume-ng-sdk</artifactId>
-      <version>1.4.0</version>
+      <version>${flume.version}</version>
       <exclusions>
         <exclusion>
           <groupId>io.netty</groupId>
@@ -52,7 +53,7 @@
     <dependency>
       <groupId>org.apache.flume</groupId>
       <artifactId>flume-ng-core</artifactId>
-      <version>1.4.0</version>
+      <version>${flume.version}</version>
       <exclusions>
         <exclusion>
           <groupId>io.netty</groupId>
@@ -62,11 +63,7 @@
           <groupId>org.apache.thrift</groupId>
           <artifactId>libthrift</artifactId>
         </exclusion>
-    </exclusions>
-    </dependency>
-    <dependency>
-      <groupId>org.scala-lang</groupId>
-      <artifactId>scala-library</artifactId>
+      </exclusions>
     </dependency>
     <dependency>
       <groupId>org.scalatest</groupId>
@@ -97,7 +94,7 @@
       <plugin>
         <groupId>org.apache.avro</groupId>
         <artifactId>avro-maven-plugin</artifactId>
-        <version>1.7.3</version>
+        <version>${avro.version}</version>
         <configuration>
           <!-- Generate the output in the same directory as the sbt-avro-plugin -->
           <outputDirectory>${project.basedir}/target/scala-${scala.binary.version}/src_managed/main/compiled_avro</outputDirectory>

external/flume/pom.xml

@@ -40,6 +40,11 @@
       <artifactId>spark-streaming_${scala.binary.version}</artifactId>
       <version>${project.version}</version>
     </dependency>
+    <dependency>
+      <groupId>org.apache.spark</groupId>
+      <artifactId>spark-streaming-flume-sink_${scala.binary.version}</artifactId>
+      <version>${project.version}</version>
+    </dependency>
     <dependency>
       <groupId>org.apache.spark</groupId>
       <artifactId>spark-streaming_${scala.binary.version}</artifactId>
@@ -50,7 +55,7 @@
     <dependency>
       <groupId>org.apache.flume</groupId>
       <artifactId>flume-ng-sdk</artifactId>
-      <version>1.4.0</version>
+      <version>${flume.version}</version>
       <exclusions>
         <exclusion>
           <groupId>io.netty</groupId>
@@ -82,11 +87,6 @@
       <artifactId>junit-interface</artifactId>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>org.apache.spark</groupId>
-      <artifactId>spark-streaming-flume-sink_2.10</artifactId>
-      <version>${project.version}</version>
-    </dependency>
   </dependencies>
   <build>
     <outputDirectory>target/scala-${scala.binary.version}/classes</outputDirectory>

pom.xml

@@ -125,6 +125,7 @@
     <protobuf.version>2.4.1</protobuf.version>
     <yarn.version>${hadoop.version}</yarn.version>
     <hbase.version>0.94.6</hbase.version>
+    <flume.version>1.4.0</flume.version>
     <zookeeper.version>3.4.5</zookeeper.version>
     <hive.version>0.12.0</hive.version>
     <parquet.version>1.4.3</parquet.version>