Fix SPARK-1256: Master web UI and Worker web UI returns a 404 error

Author: witgo <witgo@qq.com>

Closes #150 from witgo/SPARK-1256 and squashes the following commits:

08044a2 [witgo] Merge branch 'master' of https://github.com/apache/spark into SPARK-1256
c99b030 [witgo] Fix SPARK-1256

core/src/main/scala/org/apache/spark/deploy/master/ui/MasterWebUI.scala

@@ -61,7 +61,7 @@ class MasterWebUI(val master: Master, requestedPort: Int) extends Logging {
     master.applicationMetricsSystem.getServletHandlers
 
   val handlers = metricsHandlers ++ Seq[ServletContextHandler](
-    createStaticHandler(MasterWebUI.STATIC_RESOURCE_DIR, "/static/*"),
+    createStaticHandler(MasterWebUI.STATIC_RESOURCE_DIR + "/static", "/static"),
     createServletHandler("/app/json",
       createServlet((request: HttpServletRequest) => applicationPage.renderJson(request),
         master.securityMgr)),

core/src/main/scala/org/apache/spark/deploy/worker/ui/WorkerWebUI.scala

@@ -47,7 +47,7 @@ class WorkerWebUI(val worker: Worker, val workDir: File, requestedPort: Option[I
   val metricsHandlers = worker.metricsSystem.getServletHandlers
 
   val handlers = metricsHandlers ++ Seq[ServletContextHandler](
-    createStaticHandler(WorkerWebUI.STATIC_RESOURCE_BASE, "/static/*"),
+    createStaticHandler(WorkerWebUI.STATIC_RESOURCE_BASE + "/static", "/static"),
     createServletHandler("/log", createServlet((request: HttpServletRequest) => log(request),
       worker.securityMgr)),
     createServletHandler("/logPage", createServlet((request: HttpServletRequest) => logPage

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

@@ -111,10 +111,13 @@ private[spark] object JettyUtils extends Logging {
     Option(getClass.getClassLoader.getResource(resourceBase)) match {
       case Some(res) =>
         holder.setInitParameter("resourceBase", res.toString)
+        holder.setInitParameter("welcomeServlets", "false")
+        holder.setInitParameter("pathInfoOnly", "false")
       case None =>
         throw new Exception("Could not find resource path for Web UI: " + resourceBase)
     }
-    contextHandler.addServlet(holder, path)
+    contextHandler.setContextPath(path)
+    contextHandler.addServlet(holder, "/")
     contextHandler
   }
 

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

@@ -38,7 +38,7 @@ private[spark] class SparkUI(sc: SparkContext) extends Logging {
   var server: Option[Server] = None
 
   val handlers = Seq[ServletContextHandler] (
-    createStaticHandler(SparkUI.STATIC_RESOURCE_DIR, "/static/*"),
+    createStaticHandler(SparkUI.STATIC_RESOURCE_DIR + "/static", "/static"),
     createRedirectHandler("/stages", "/")
   )
   val storage = new BlockManagerUI(sc)