Merge pull request #114 from soulmachine/master

A little revise for the document

docker/spark-test/README.md

 Spark Docker files usable for testing and development purposes.
 
 These images are intended to be run like so:
-docker run -v $SPARK_HOME:/opt/spark spark-test-master
-docker run -v $SPARK_HOME:/opt/spark spark-test-worker <master_ip>
+
+	docker run -v $SPARK_HOME:/opt/spark spark-test-master
+	docker run -v $SPARK_HOME:/opt/spark spark-test-worker <master_ip>
 
 Using this configuration, the containers will have their Spark directories
-mounted to your actual SPARK_HOME, allowing you to modify and recompile
+mounted to your actual `SPARK_HOME`, allowing you to modify and recompile
 your Spark source and have them immediately usable in the docker images
 (without rebuilding them).