SPARK-2115: Stage kill link is too close to stage details link

Moved (kill) link to the right side. Add confirmation dialog when (kill) link is clicked.

Author: Masayoshi TSUZUKI <[email protected]>

Closes apache#1350 from tsudukim/feature/SPARK-2115 and squashes the following commits:

e2263b0 [Masayoshi TSUZUKI] Moved (kill) link to the right side. Add confirmation dialog when (kill) link is clicked.

Author: tsudukim

core/src/main/resources/org/apache/spark/ui/static/webui.css

@@ -81,7 +81,9 @@ table.sortable thead {
 
 span.kill-link {
   margin-right: 2px;
+  margin-left: 20px;
   color: gray;
+  float: right;
 }
 
 span.kill-link a {

core/src/main/scala/org/apache/spark/ui/jobs/StageTable.scala

@@ -89,7 +89,8 @@ private[ui] class StageTableBase(
     // scalastyle:off
     val killLink = if (killEnabled) {
       <span class="kill-link">
-        (<a href={"%s/stages/stage/kill?id=%s&terminate=true".format(UIUtils.prependBaseUri(basePath), s.stageId)}>kill</a>)
+        (<a href={"%s/stages/stage/kill?id=%s&terminate=true".format(UIUtils.prependBaseUri(basePath), s.stageId)}
+            onclick={"return window.confirm('Are you sure you want to kill stage %s ?');".format(s.stageId)}>kill</a>)
       </span>
     }
     // scalastyle:on
@@ -109,7 +110,7 @@ private[ui] class StageTableBase(
 
     listener.stageIdToDescription.get(s.stageId)
       .map(d => <div><em>{d}</em></div><div>{nameLink} {killLink}</div>)
-      .getOrElse(<div>{killLink} {nameLink} {details}</div>)
+      .getOrElse(<div>{nameLink} {killLink} {details}</div>)
   }
 
   protected def stageRow(s: StageInfo): Seq[Node] = {