SPARK-1164 Deprecated reduceByKeyToDriver as it is an alias for reduceByKeyLocally

Author: Prashant Sharma <prashant.s@imaginea.com>

Closes #72 from ScrapCodes/SPARK-1164/deprecate-reducebykeytodriver and squashes the following commits:

ee521cd [Prashant Sharma] SPARK-1164 Deprecated reduceByKeyToDriver as it is an alias for reduceByKeyLocally
SPARK-1178: missing document of spark.scheduler.revive.interval

https://spark-project.atlassian.net/browse/SPARK-1178

The configuration on spark.scheduler.revive.interval is undocumented but actually used

https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/scheduler/cluster/CoarseGrainedSchedulerBackend.scala#L64

Author: CodingCat <zhunansjtu@gmail.com>

Closes #74 from CodingCat/SPARK-1178 and squashes the following commits:

783ec69 [CodingCat] missing document of spark.scheduler.revive.interval
SPARK-1109 wrong API docs for pyspark map function

Author: Prashant Sharma <prashant.s@imaginea.com>

Closes #73 from ScrapCodes/SPARK-1109/wrong-API-docs and squashes the following commits:

1a55b58 [Prashant Sharma] SPARK-1109 wrong API docs for pyspark map function
SPARK-1171: when executor is removed, we should minus totalCores instead of just freeCores on that executor

https://spark-project.atlassian.net/browse/SPARK-1171

When the executor is removed, the current implementation will only minus the freeCores of that executor. Actually we should minus the totalCores...

Author: CodingCat <zhunansjtu@gmail.com>
Author: Nan Zhu <CodingCat@users.noreply.github.com>

Closes #63 from CodingCat/simplify_CoarseGrainedSchedulerBackend and squashes the following commits:

f6bf93f [Nan Zhu] code clean
19c2bb4 [CodingCat] use copy idiom to reconstruct the workerOffers
43c13e9 [CodingCat] keep WorkerOffer immutable
af470d3 [CodingCat] style fix
0c0e409 [CodingCat] simplify the implementation of CoarseGrainedSchedulerBackend
Merge branch 'master' of github.com:apache/spark into csd-1.0