[SPARK-4096][YARN]let ApplicationMaster accept executor memory argument in same format as JVM memory strings

Here `ApplicationMaster` accept executor memory argument only in number format, we should let it accept JVM style memory strings as well.

Author: WangTaoTheTonic <barneystinson@aliyun.com>

Closes #2955 from WangTaoTheTonic/modifyDesc and squashes the following commits:

ab98c70 [WangTaoTheTonic] append parameter passed in
3779767 [WangTaoTheTonic] Update executor memory description in the help message
[SPARK-3657] yarn alpha YarnRMClientImpl throws NPE appMasterRequest.setTrackingUrl starting spark-shell

tgravescs reported this issue.

Following is quoted from tgravescs' report.

YarnRMClientImpl.registerApplicationMaster can throw null pointer exception when setting the trackingurl if its empty:

    appMasterRequest.setTrackingUrl(new URI(uiAddress).getAuthority())

I hit this just start spark-shell without the tracking url set.

14/09/23 16:18:34 INFO yarn.YarnRMClientImpl: Connecting to ResourceManager at kryptonitered-jt1.red.ygrid.yahoo.com/98.139.154.99:8030
Exception in thread "main" java.lang.NullPointerException
        at org.apache.hadoop.yarn.proto.YarnServiceProtos$RegisterApplicationMasterRequestProto$Builder.setTrackingUrl(YarnServiceProtos.java:710)
        at org.apache.hadoop.yarn.api.protocolrecords.impl.pb.RegisterApplicationMasterRequestPBImpl.setTrackingUrl(RegisterApplicationMasterRequestPBImpl.java:132)
        at org.apache.spark.deploy.yarn.YarnRMClientImpl.registerApplicationMaster(YarnRMClientImpl.scala:102)
        at org.apache.spark.deploy.yarn.YarnRMClientImpl.register(YarnRMClientImpl.scala:55)
        at org.apache.spark.deploy.yarn.YarnRMClientImpl.register(YarnRMClientImpl.scala:38)
        at org.apache.spark.deploy.yarn.ApplicationMaster.registerAM(ApplicationMaster.scala:168)
        at org.apache.spark.deploy.yarn.ApplicationMaster.runExecutorLauncher(ApplicationMaster.scala:206)
        at org.apache.spark.deploy.yarn.ApplicationMaster.run(ApplicationMaster.scala:120)

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #2981 from sarutak/SPARK-3657-2 and squashes the following commits:

e2fd6bc [Kousuke Saruta] Merge branch 'master' of git://git.apache.org/spark into SPARK-3657
70b8882 [Kousuke Saruta] Fixed NPE thrown
[SPARK-4089][Doc][Minor] The version number of Spark in _config.yaml is wrong.

The version number of Spark in docs/_config.yaml for master branch should be 1.2.0 for now.

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #2943 from sarutak/SPARK-4089 and squashes the following commits:

aba7fb4 [Kousuke Saruta] Fixed the version number of Spark in _config.yaml
[SPARK-4065] Add check for IPython on Windows

This issue employs logic similar to the bash launcher (pyspark) to check
if IPTYHON=1, and if so launch ipython with options in IPYTHON_OPTS.
This fix assumes that ipython is available in the system Path, and can
be invoked with a plain "ipython" command.

Author: Michael Griffiths <msjgriffiths@gmail.com>

Closes #2910 from msjgriffiths/pyspark-windows and squashes the following commits:

ef34678 [Michael Griffiths] Change build message to comply with [SPARK-3775]
361e3d8 [Michael Griffiths] [SPARK-4065] Add check for IPython on Windows
9ce72d1 [Michael Griffiths] [SPARK-4065] Add check for IPython on Windows
[SPARK-4058] [PySpark] Log file name is hard coded even though there is a variable '$LOG_FILE '

In a script 'python/run-tests', log file name is represented by a variable 'LOG_FILE' and it is used in run-tests. But, there are some hard-coded log file name in the script.

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #2905 from sarutak/SPARK-4058 and squashes the following commits:

7710490 [Kousuke Saruta] Fixed python/run-tests not to use hard-coded log file name