MAINTENANCE: Automated closing of pull requests.

This commit exists to close the following pull requests on Github:

Closes #1696 (close requested by 'pwendell')
Closes #1384 (close requested by 'pwendell')
Closes #845 (close requested by 'pwendell')
Closes #81 (close requested by 'pwendell')
Closes #1528 (close requested by 'pwendell')
Closes #1018 (close requested by 'pwendell')
[SPARK-3135] Avoid extra mem copy in TorrentBroadcast via ByteArrayChunkOutputStream

This also enables supporting broadcast variables larger than 2G.

Author: Reynold Xin <rxin@apache.org>

Closes #2054 from rxin/ByteArrayChunkOutputStream and squashes the following commits:

618d9c8 [Reynold Xin] Code review.
93f5a51 [Reynold Xin] Added comments.
ee88e73 [Reynold Xin] to -> until
bbd1cb1 [Reynold Xin] Renamed a variable.
36f4d01 [Reynold Xin] Sort imports.
8f1a8eb [Reynold Xin] [SPARK-3135] Created ByteArrayChunkOutputStream and used it to avoid memory copy in TorrentBroadcast.
[SPARK-3342] Add SSDs to block device mapping

On `m3.2xlarge` instances the 2x80GB SSDs are inaccessible if not added to the block device mapping when the instance is created. They work when added with this patch. I have not tested this with other instance types, and I do not know much about this script and EC2 deployment in general. Maybe this code needs to depend on the instance type.

The requirement for this mapping is described in the AWS docs at:
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/InstanceStorage.html#InstanceStore_UsageScenarios

"For M3 instances, you must specify instance store volumes in the block
device mapping for the instance. When you launch an M3 instance, we
ignore any instance store volumes specified in the block device mapping
for the AMI."

Author: Daniel Darabos <darabos.daniel@gmail.com>

Closes #2081 from darabos/patch-1 and squashes the following commits:

1ceb2c8 [Daniel Darabos] Use %d string interpolation instead of {}.
a1854d7 [Daniel Darabos] Only specify ephemeral device mapping for M3.
e0d9e37 [Daniel Darabos] Create ephemeral device mapping based on get_num_disks().
6b116a6 [Daniel Darabos] Add SSDs to block device mapping
SPARK-2636: Expose job ID in JobWaiter API

This PR adds the async actions to the Java API. User can call these async actions to get the FutureAction and use JobWaiter (for SimpleFutureAction) to retrieve job Id.

Author: lirui <rui.li@intel.com>

Closes #2176 from lirui-intel/SPARK-2636 and squashes the following commits:

ccaafb7 [lirui] SPARK-2636: fix java doc
5536d55 [lirui] SPARK-2636: mark the async API as experimental
e2e01d5 [lirui] SPARK-2636: add mima exclude
0ca320d [lirui] SPARK-2636: fix method name & javadoc
3fa39f7 [lirui] SPARK-2636: refine the patch
af4f5d9 [lirui] SPARK-2636: remove unused imports
843276c [lirui] SPARK-2636: only keep foreachAsync in the java API
fbf5744 [lirui] SPARK-2636: add more async actions for java api
1b25abc [lirui] SPARK-2636: expose some fields in JobWaiter
d09f732 [lirui] SPARK-2636: fix build
eb1ee79 [lirui] SPARK-2636: change some parameters in SimpleFutureAction to member field
6e2b87b [lirui] SPARK-2636: add java API for async actions
[MLlib] Squash bug in IndexedRowMatrix

Kill this bug fast before it does damage.

Author: Reza Zadeh <rizlar@gmail.com>

Closes #2224 from rezazadeh/indexrmbug and squashes the following commits:

53386d6 [Reza Zadeh] Squash bug in IndexedRowMatrix
SPARK-3331 [BUILD] PEP8 tests fail because they check unzipped py4j code

PEP8 tests run on files under "./python", but unzipped py4j code is found at "./python/build/py4j". Py4J code fails style checks and can fail ./dev/run-tests if this code is present locally.

Author: Sean Owen <sowen@cloudera.com>

Closes #2222 from srowen/SPARK-3331 and squashes the following commits:

34711ec [Sean Owen] Restrict lint check to pyspark/, since the local directory can contain unzipped py4j code in build/py4j