Merge pull request #833 from rxin/ui

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

core/src/main/scala/spark/deploy/master/ui/IndexPage.scala

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

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

core/src/main/scala/spark/ui/UIWorkloadGenerator.scala

core/src/main/scala/spark/ui/env/EnvironmentUI.scala

core/src/main/scala/spark/ui/exec/ExecutorsUI.scala

core/src/main/scala/spark/ui/jobs/IndexPage.scala

core/src/main/scala/spark/ui/jobs/PoolPage.scala

core/src/main/scala/spark/ui/jobs/PoolTable.scala

core/src/main/scala/spark/ui/jobs/StagePage.scala

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

core/src/main/scala/spark/ui/storage/RDDPage.scala