Add missing init for DynamoDB client in Worker (#51)

When the dynamoDBEndpoint configuration property was added, not all paths that
should have made use of it were updated.  Both paths now use the config value to
set up the DynamoDB client.

src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/Worker.java

@@ -1064,6 +1064,11 @@ public Worker build() {
                 dynamoDBClient.setRegion(region);
                 LOG.debug("The region of Amazon DynamoDB client has been set to " + config.getRegionName());
             }
+            // If a dynamoDB endpoint was explicitly specified, use it to set the DynamoDB endpoint.
+            if (config.getDynamoDBEndpoint() != null) {
+                dynamoDBClient.setEndpoint(config.getDynamoDBEndpoint());
+                LOG.debug("The endpoint of Amazon DynamoDB client has been set to " + config.getDynamoDBEndpoint());
+            }
             // If a kinesis endpoint was explicitly specified, use it to set the region of kinesis.
             if (config.getKinesisEndpoint() != null) {
                 kinesisClient.setEndpoint(config.getKinesisEndpoint());