[SPARK-2124] Move aggregation into shuffle implementations

This PR is a sub-task of SPARK-2044 to move the execution of aggregation into shuffle implementations.

I leave `CoGoupedRDD` and `SubtractedRDD` unchanged because they have their implementations of aggregation. I'm not sure is it suitable to change these two RDDs.

Also I do not move sort related code of `OrderedRDDFunctions` into shuffle, this will be solved in another sub-task.

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

Closes #1064 from jerryshao/SPARK-2124 and squashes the following commits:

4a05a40 [jerryshao] Modify according to comments
1f7dcc8 [jerryshao] Style changes
50a2fd6 [jerryshao] Fix test suite issue after moving aggregator to Shuffle reader and writer
1a96190 [jerryshao] Code modification related to the ShuffledRDD
308f635 [jerryshao] initial works of move combiner to ShuffleManager's reader and writer
[SPARK-2252] Fix MathJax for HTTPs.

Found out about this from the Hacker News link to GraphX which was using HTTPs.

@mengxr

Author: Reynold Xin <rxin@apache.org>

Closes #1189 from rxin/mllib-doc and squashes the following commits:

5328be0 [Reynold Xin] [SPARK-2252] Fix MathJax for HTTPs.
SPARK-1937: fix issue with task locality

Don't check executor/host availability when creating a TaskSetManager. Because the executors may haven't been registered when the TaskSetManager is created, in which case all tasks will be considered "has no preferred locations", and thus losing data locality in later scheduling.

Author: Rui Li <rui.li@intel.com>
Author: lirui-intel <rui.li@intel.com>

Closes #892 from lirui-intel/delaySchedule and squashes the following commits:

8444d7c [Rui Li] fix code style
fafd57f [Rui Li] keep locality constraints within the valid levels
18f9e05 [Rui Li] restrict allowed locality
5b3fb2f [Rui Li] refine UT
99f843e [Rui Li] add unit test and fix bug
fff4123 [Rui Li] fix computing valid locality levels
685ed3d [Rui Li] remove delay shedule for pendingTasksWithNoPrefs
7b0177a [Rui Li] remove redundant code
c7b93b5 [Rui Li] revise patch
3d7da02 [lirui-intel] Update TaskSchedulerImpl.scala
cab4c71 [Rui Li] revised patch
539a578 [Rui Li] fix code style
cf0d6ac [Rui Li] fix code style
3dfae86 [Rui Li] re-compute pending tasks when new host is added
a225ac2 [Rui Li] SPARK-1937: fix issue with task locality
HOTFIX: Disabling tests per SPARK-2264
Fix broken Json tests.

The assertJsonStringEquals method was missing an "assert" so
did not actually check that the strings were equal. This commit
adds the missing assert and fixes subsequently revealed problems
with the JsonProtocolSuite.

@andrewor14 I changed some of the test functionality to match what it
looks like you intended based on the expected strings -- let me know if
anything here looks wrong.

Author: Kay Ousterhout <kayousterhout@gmail.com>

Closes #1198 from kayousterhout/json_test_fix and squashes the following commits:

77f858f [Kay Ousterhout] Fix broken Json tests.
[SPARK-2264][SQL] Fix failing CachedTableSuite

Author: Michael Armbrust <michael@databricks.com>

Closes #1201 from marmbrus/fixCacheTests and squashes the following commits:

9d87ed1 [Michael Armbrust] Use analyzer (which runs to fixed point) instead of manually removing analysis operators.
[SPARK-1112, 2156] Bootstrap to fetch the driver's Spark properties.

This is an alternative solution to #1124 . Before launching the executor backend, we first fetch driver's spark properties and use it to overwrite executor's spark properties. This should be better than #1124.

@pwendell Are there spark properties that might be different on the driver and on the executors?

Author: Xiangrui Meng <meng@databricks.com>

Closes #1132 from mengxr/akka-bootstrap and squashes the following commits:

77ff32d [Xiangrui Meng] organize imports
68e1dfb [Xiangrui Meng] use timeout from AkkaUtils; remove props from RegisteredExecutor
46d332d [Xiangrui Meng] fix a test
7947c18 [Xiangrui Meng] increase slack size for akka
4ab696a [Xiangrui Meng] bootstrap to retrieve driver spark conf
[SQL]Add base row updating methods for JoinedRow

This will be helpful in join operators.

Author: Cheng Hao <hao.cheng@intel.com>

Closes #1187 from chenghao-intel/joinedRow and squashes the following commits:

87c19e3 [Cheng Hao] Add base row set methods for JoinedRow
Autodetect JAVA_HOME on RPM-based systems

Author: Matthew Farrellee <matt@redhat.com>

Closes #1185 from mattf/master-1 and squashes the following commits:

42150fc [Matthew Farrellee] Autodetect JAVA_HOME on RPM-based systems
Fix possible null pointer in acumulator toString

Author: Michael Armbrust <michael@databricks.com>

Closes #1204 from marmbrus/nullPointerToString and squashes the following commits:

35b5fce [Michael Armbrust] Fix possible null pointer in acumulator toString
SPARK-2248: spark.default.parallelism does not apply in local mode

Author: witgo <witgo@qq.com>

Closes #1194 from witgo/SPARK-2248 and squashes the following commits:

6ac950b [witgo] spark.default.parallelism does not apply in local mode
Merge branch 'master' of https://github.com/apache/spark into SPARK-1291