Fixed Bug Flink-978

https://issues.apache.org/jira/browse/FLINK-978

Author: Jonathan <Jonathan@Hasenburg.de>

Closes #46 from JonathanH5/fixWebI and squashes the following commits:

13a7d41 [Jonathan] Fixed Bug Flink-978

stratosphere-runtime/src/main/java/eu/stratosphere/nephele/managementgraph/ManagementVertex.java

@@ -318,7 +318,7 @@ public final class ManagementVertex extends ManagementAttachment implements IORe
 		json.append("\"vertexid\": \"" + this.getID() + "\",");
 		json.append("\"vertexname\": \"" + StringUtils.escapeHtml(this.toString()) + "\",");
 		json.append("\"vertexstatus\": \"" + this.getExecutionState() + "\",");
-		json.append("\"vertexinstancename\": \"" + this.getInstanceName() + "\",");
+		json.append("\"vertexinstancename\": \"" + this.getInstanceName() + "\"");
 		json.append("}");
 		return json.toString();
 	}