SPARK-1565 (Addendum): Replace `run-example` with `spark-submit`.

Gives a nicely formatted message to the user when `run-example` is run to
tell them to use `spark-submit`.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #704 from pwendell/examples and squashes the following commits:

1996ee8 [Patrick Wendell] Feedback form Andrew
3eb7803 [Patrick Wendell] Suggestions from TD
2474668 [Patrick Wendell] SPARK-1565 (Addendum): Replace `run-example` with `spark-submit`.
SPARK-1775: Unneeded lock in ShuffleMapTask.deserializeInfo

This was used in the past to have a cache of deserialized ShuffleMapTasks, but that's been removed, so there's no need for a lock. It slows down Spark when task descriptions are large, e.g. due to large lineage graphs or local variables.

Author: Sandeep <sandeep@techaddict.me>

Closes #707 from techaddict/SPARK-1775 and squashes the following commits:

18d8ebf [Sandeep] SPARK-1775: Unneeded lock in ShuffleMapTask.deserializeInfo This was used in the past to have a cache of deserialized ShuffleMapTasks, but that's been removed, so there's no need for a lock. It slows down Spark when task descriptions are large, e.g. due to large lineage graphs or local variables.
MINOR: Removing dead code.

Meant to do this when patching up the last merge.
Converted bang to ask to avoid scary warning when a block is removed

Removing a block through the blockmanager gave a scary warning messages in the driver.
```
2014-05-08 20:16:19,172 WARN BlockManagerMasterActor: Got unknown message: true
2014-05-08 20:16:19,172 WARN BlockManagerMasterActor: Got unknown message: true
2014-05-08 20:16:19,172 WARN BlockManagerMasterActor: Got unknown message: true
```

This is because the [BlockManagerSlaveActor](https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/storage/BlockManagerSlaveActor.scala#L44) would send back an acknowledgement ("true"). But the BlockManagerMasterActor would have sent the RemoveBlock message as a send, not as ask(), so would reject the receiver "true" as a unknown message.
@pwendell

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes #708 from tdas/bm-fix and squashes the following commits:

ed4ef15 [Tathagata Das] Converted bang to ask to avoid scary warning when a block is removed.
[SPARK-1760]: fix building spark with maven documentation

Author: witgo <witgo@qq.com>

Closes #712 from witgo/building-with-maven and squashes the following commits:

215523b [witgo] fix building spark with maven documentation