[SPARK-4330][Doc] Link to proper URL for YARN overview

In running-on-yarn.md, a link to YARN overview is here.
But the URL is to YARN alpha's.
It should be stable's.

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #3196 from sarutak/SPARK-4330 and squashes the following commits:

30baa21 [Kousuke Saruta] Fixed running-on-yarn.md to point proper URL for YARN
[SPARK-4324] [PySpark] [MLlib] support numpy.array for all MLlib API

This PR check all of the existing Python MLlib API to make sure that numpy.array is supported as Vector (also RDD of numpy.array).

It also improve some docstring and doctest.

cc mateiz mengxr

Author: Davies Liu <davies@databricks.com>

Closes #3189 from davies/numpy and squashes the following commits:

d5057c4 [Davies Liu] fix tests
6987611 [Davies Liu] support numpy.array for all MLlib API
[SPARK-4307] Initialize FileDescriptor lazily in FileRegion.

Netty's DefaultFileRegion requires a FileDescriptor in its constructor, which means we need to have a opened file handle. In super large workloads, this could lead to too many open files due to the way these file descriptors are cleaned. This pull request creates a new LazyFileRegion that initializes the FileDescriptor when we are sending data for the first time.

Author: Reynold Xin <rxin@databricks.com>
Author: Reynold Xin <rxin@apache.org>

Closes #3172 from rxin/lazyFD and squashes the following commits:

0bdcdc6 [Reynold Xin] Added reference to Netty's DefaultFileRegion
d4564ae [Reynold Xin] Added SparkConf to the ctor argument of IndexShuffleBlockManager.
6ed369e [Reynold Xin] Code review feedback.
04cddc8 [Reynold Xin] [SPARK-4307] Initialize FileDescriptor lazily in FileRegion.
[SPARK-4295][External]Fix exception in SparkSinkSuite

Handle exception in SparkSinkSuite, please refer to [SPARK-4295]

Author: maji2014 <maji3@asiainfo.com>

Closes #3177 from maji2014/spark-4295 and squashes the following commits:

312620a [maji2014] change a new statement for spark-4295
24c3d21 [maji2014] add log4j.properties for SparkSinkSuite and spark-4295
c807bf6 [maji2014] Fix exception in SparkSinkSuite
[SPARK-2492][Streaming] kafkaReceiver minor changes to align with Kafka 0.8

Update the KafkaReceiver's behavior when auto.offset.reset is set.

In Kafka 0.8, `auto.offset.reset` is a hint for out-range offset to seek to the beginning or end of the partition. While in the previous code `auto.offset.reset` is a enforcement to seek to the beginning or end immediately, this is different from Kafka 0.8 defined behavior.

Also deleting extesting ZK metadata in Receiver when multiple consumers are launched will introduce issue as mentioned in [SPARK-2383](https://issues.apache.org/jira/browse/SPARK-2383).

So Here we change to offer user to API to explicitly reset offset before create Kafka stream, while in the meantime keep the same behavior as Kafka 0.8 for parameter `auto.offset.reset`.

@tdas, would you please review this PR? Thanks a lot.

Author: jerryshao <saisai.shao@intel.com>

Closes #1420 from jerryshao/kafka-fix and squashes the following commits:

d6ae94d [jerryshao] Address the comment to remove the resetOffset() function
de3a4c8 [jerryshao] Fix compile error
4a1c3f9 [jerryshao] Doc changes
b2c1430 [jerryshao] Move offset reset to a helper function to let user explicitly delete ZK metadata by calling this API
fac8fd6 [jerryshao] Changes to align with Kafka 0.8
[Streaming][Minor]Replace some 'if-else' in Clock

Replace some 'if-else' statement by math.min and math.max in Clock.scala

Author: huangzhaowei <carlmartinmax@gmail.com>

Closes #3088 from SaintBacchus/StreamingClock and squashes the following commits:

7b7f8e7 [huangzhaowei] [Streaming][Minor]Replace some 'if-else' in Clock
Merge remote-tracking branch 'upstream/master'
Renamed variable and moved method.