[SPARK-1273] use doi links in mllib-guide

Author: Xiangrui Meng <meng@databricks.com>

Closes #198 from mengxr/branch-0.9 and squashes the following commits:

39c74ff [Xiangrui Meng] use doi links in mllib-guide
SPARK-1284: Fix improper use of SimpleDateFormat

`SimpleDateFormat` is not thread-safe. Some places use the same SimpleDateFormat object without safeguard in the multiple threads. It will cause that the Web UI displays improper date.

This PR creates a new `SimpleDateFormat` every time when it's necessary. Another solution is using `ThreadLocal` to store a `SimpleDateFormat` in each thread. If this PR impacts the performance, I can change to the latter one.

Author: zsxwing <zsxwing@gmail.com>

Closes #179 from zsxwing/SPARK-1278 and squashes the following commits:

21fabd3 [zsxwing] SPARK-1278: Fix improper use of SimpleDateFormat

Conflicts:

	core/src/main/scala/org/apache/spark/scheduler/JobLogger.scala
	core/src/main/scala/org/apache/spark/ui/jobs/JobProgressUI.scala
	core/src/main/scala/org/apache/spark/ui/jobs/StagePage.scala
	core/src/main/scala/org/apache/spark/ui/jobs/StageTable.scala
	core/src/main/scala/org/apache/spark/util/FileLogger.scala
Fix to Stage UI to display numbers on progress bar

Fixes an issue on Stage UI to display numbers on progress bar which are today hidden behind the progress bar div. Please refer to the attached images to see the issue.
![screen shot 2014-03-21 at 4 48 46 pm](https://f.cloud.github.com/assets/563652/2489083/8c127e80-b153-11e3-807c-048ebd45104b.png)
![screen shot 2014-03-21 at 4 49 00 pm](https://f.cloud.github.com/assets/563652/2489084/8c12cf5c-b153-11e3-8747-9d93ff6fceb4.png)

Author: Emtiaz Ahmed <emtiazahmed@gmail.com>

Closes #201 from emtiazahmed/master and squashes the following commits:

a7964fe [Emtiaz Ahmed] Fix to Stage UI to display numbers on progress bar

(cherry picked from commit 646e55405b433fdedc9601dab91f99832b641f87)
Signed-off-by: Aaron Davidson <aaron@databricks.com>
Updated CHANGES.txt file.
Removed all occurences of incubator from all the pom.xml.
[maven-release-plugin] prepare release v0.9.1-rc1
Merge tag 'v0.9.1-rc1' of github.com:apache/spark into csd-2.10

[maven-release-plugin]  copy for tag v0.9.1-rc1

Conflicts:
	assembly/pom.xml
	bagel/pom.xml
	core/pom.xml
	examples/pom.xml
	external/flume/pom.xml
	external/kafka/pom.xml
	external/mqtt/pom.xml
	external/twitter/pom.xml
	external/zeromq/pom.xml
	graphx/pom.xml
	mllib/pom.xml
	pom.xml
	repl/pom.xml
	streaming/pom.xml
	tools/pom.xml
	yarn/pom.xml