[SPARK-12673][UI] Add missing uri prepending for job description

Otherwise the url will be failed to proxy to the right one if in YARN mode. Here is the screenshot:

![screen shot 2016-01-06 at 5 28 26 pm](https://cloud.githubusercontent.com/assets/850797/12139632/bbe78ecc-b49c-11e5-8932-94e8b3622a09.png)

Author: jerryshao <sshao@hortonworks.com>

Closes #10618 from jerryshao/SPARK-12673.

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

@@ -224,10 +224,10 @@ private[ui] class AllJobsPage(parent: JobsTab) extends WebUIPage("") {
       }
       val formattedDuration = duration.map(d => UIUtils.formatDuration(d)).getOrElse("Unknown")
       val formattedSubmissionTime = job.submissionTime.map(UIUtils.formatDate).getOrElse("Unknown")
-      val jobDescription = UIUtils.makeDescription(lastStageDescription, parent.basePath)
+      val basePathUri = UIUtils.prependBaseUri(parent.basePath)
+      val jobDescription = UIUtils.makeDescription(lastStageDescription, basePathUri)
 
-      val detailUrl =
-        "%s/jobs/job?id=%s".format(UIUtils.prependBaseUri(parent.basePath), job.jobId)
+      val detailUrl = "%s/jobs/job?id=%s".format(basePathUri, job.jobId)
       <tr id={"job-" + job.jobId}>
         <td sorttable_customkey={job.jobId.toString}>
           {job.jobId} {job.jobGroup.map(id => s"($id)").getOrElse("")}