[SPARK-4920][UI] add version on master and worker page for standalone mode

Author: Zhang, Liye <[email protected]>

Closes #3769 from liyezhang556520/spark-4920_WebVersion and squashes the following commits:

3bb7e0d [Zhang, Liye] add version on master and worker page

(cherry picked from commit 9077e72)
Signed-off-by: Josh Rosen <[email protected]>

Author: liyezhang556520

core/src/main/scala/org/apache/spark/ui/UIUtils.scala

@@ -234,8 +234,9 @@ private[spark] object UIUtils extends Logging {
             <div class="span12">
               <h3 style="vertical-align: middle; display: inline-block;">
                 <a style="text-decoration: none" href={prependBaseUri("/")}>
-                  <img src={prependBaseUri("/static/spark-logo-77x50px-hd.png")}
-                       style="margin-right: 15px;" />
+                  <img src={prependBaseUri("/static/spark-logo-77x50px-hd.png")} />
+                  <span class="version" 
+                        style="margin-right: 15px;">{org.apache.spark.SPARK_VERSION}</span>
                 </a>
                 {title}
               </h3>