Update dependency versions for CVEs

* zookeeper CVE-2019-0201
* checkstyle CVE-2019-9658
* spark CVE-2018-17190 (updated, but not fully resolved, since no
  version of spark fixes this yet)

Build formatted an unrelated class.

pom.xml

@@ -189,7 +189,7 @@
         <!-- This was added to ensure project only uses public API -->
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-checkstyle-plugin</artifactId>
-        <version>3.0.0</version>
+        <version>3.1.0</version>
         <executions>
           <execution>
             <id>check-style</id>
@@ -202,7 +202,7 @@
           <dependency>
             <groupId>com.puppycrawl.tools</groupId>
             <artifactId>checkstyle</artifactId>
-            <version>8.17</version>
+            <version>8.21</version>
           </dependency>
         </dependencies>
         <configuration>

spark/pom.xml

@@ -32,7 +32,7 @@
     <hadoop.version>3.2.0</hadoop.version>
     <maven.compiler.source>1.8</maven.compiler.source>
     <maven.compiler.target>1.8</maven.compiler.target>
-    <zookeeper.version>3.4.13</zookeeper.version>
+    <zookeeper.version>3.4.14</zookeeper.version>
   </properties>
   <dependencyManagement>
     <dependencies>
@@ -62,7 +62,7 @@
     <dependency>
       <groupId>org.apache.spark</groupId>
       <artifactId>spark-core_2.11</artifactId>
-      <version>2.4.0</version>
+      <version>2.4.3</version>
     </dependency>
   </dependencies>
   <build>

src/main/java/org/apache/accumulo/examples/client/SequentialBatchWriter.java

@@ -16,15 +16,16 @@
  */
 package org.apache.accumulo.examples.client;
 
-import com.beust.jcommander.Parameter;
+import java.util.Random;
+
 import org.apache.accumulo.core.client.*;
 import org.apache.accumulo.core.data.Mutation;
 import org.apache.accumulo.core.data.Value;
 import org.apache.accumulo.examples.cli.ClientOpts;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.Random;
+import com.beust.jcommander.Parameter;
 
 /**
  * Simple example for writing random data in sequential order to Accumulo.