Streaming programming guide typos

Fix a bad Java code sample and a broken link in the streaming programming guide.

Author: Clément MATHIEU <clement@unportant.info>

Closes #1286 from cykl/streaming-programming-guide-typos and squashes the following commits:

b0908cb [Clément MATHIEU] Fix broken URL
9d3c535 [Clément MATHIEU] Spark streaming requires at least two working threads (scala version was OK)

docs/streaming-programming-guide.md

@@ -148,7 +148,7 @@ import org.apache.spark.streaming.*;
 import org.apache.spark.streaming.api.java.*;
 import scala.Tuple2;
 // Create a StreamingContext with a local master
-JavaStreamingContext jssc = new JavaStreamingContext("local", "JavaNetworkWordCount", new Duration(1000))
+JavaStreamingContext jssc = new JavaStreamingContext("local[2]", "JavaNetworkWordCount", new Duration(1000))
 {% endhighlight %}
 
 Using this context, we then create a new DStream
@@ -216,7 +216,7 @@ jssc.awaitTermination();   // Wait for the computation to terminate
 {% endhighlight %}
 
 The complete code can be found in the Spark Streaming example
-[JavaNetworkWordCount]({{site.SPARK_GITHUB_URL}}/blob/master/examples/src/main/java/index.html?org/apache/spark/examples/streaming/JavaNetworkWordCount.java).
+[JavaNetworkWordCount]({{site.SPARK_GITHUB_URL}}/blob/master/examples/src/main/java/org/apache/spark/examples/streaming/JavaNetworkWordCount.java).
 <br>
 
 </div>