[SPARK-4896] don’t redundantly overwrite executor JAR deps

Author: Ryan Williams <ryan.blake.williams@gmail.com>

Closes #2848 from ryan-williams/fetch-file and squashes the following commits:

c14daff [Ryan Williams] Fix copy that was changed to a move inadvertently
8e39c16 [Ryan Williams] code review feedback
788ed41 [Ryan Williams] don’t redundantly overwrite executor JAR deps

(cherry picked from commit 7981f969762e77f1752ef8f86c546d4fc32a1a4f)
Signed-off-by: Josh Rosen <joshrosen@databricks.com>
change signature of example to match released code

the signature of registerKryoClasses is actually of Array[Class[_]]  not Seq

Author: Eran Medan <ehrann.mehdan@gmail.com>

Closes #3747 from eranation/patch-1 and squashes the following commits:

ee9885d [Eran Medan] change signature of example to match released code
SPARK-2641: Passing num executors to spark arguments from properties file

Since we can set spark executor memory and executor cores using property file, we must also be allowed to set the executor instances.

Author: Kanwaljit Singh <kanwaljit.singh@guavus.com>

Closes #1657 from kjsingh/branch-1.0 and squashes the following commits:

d8a5a12 [Kanwaljit Singh] SPARK-2641: Fixing how spark arguments are loaded from properties file for num executors

Conflicts:
	core/src/main/scala/org/apache/spark/deploy/SparkSubmitArguments.scala
[SPARK-4140] Document dynamic allocation

Once the external shuffle service is also documented, the dynamic allocation section will link to it. Let me know if the whole dynamic allocation should be moved to its separate page; I personally think the organization might be cleaner that way.

This patch builds on top of oza's work in #3689.

aarondav pwendell

Author: Andrew Or <andrew@databricks.com>
Author: Tsuyoshi Ozawa <ozawa.tsuyoshi@gmail.com>

Closes #3731 from andrewor14/document-dynamic-allocation and squashes the following commits:

1281447 [Andrew Or] Address a few comments
b9843f2 [Andrew Or] Document the configs as well
246fb44 [Andrew Or] Merge branch 'SPARK-4839' of github.com:oza/spark into document-dynamic-allocation
8c64004 [Andrew Or] Add documentation for dynamic allocation (without configs)
6827b56 [Tsuyoshi Ozawa] Fixing a documentation of spark.dynamicAllocation.enabled.
53cff58 [Tsuyoshi Ozawa] Adding a documentation about dynamic resource allocation.

(cherry picked from commit 15c03e1e0efac29855f32984da7c6b0321f0e37a)
Signed-off-by: Andrew Or <andrew@databricks.com>