Worker registration logging fix

Author: Andrew Ash <andrew@andrewash.com>

Closes #608 from ash211/patch-7 and squashes the following commits:

bd85f2a [Andrew Ash] Worker registration logging fix
Fix typos in Spark Streaming programming guide

Author: Andrew Or <andrewor14@gmail.com>

Closes #536 from andrewor14/streaming-typos and squashes the following commits:

a05faa6 [Andrew Or] Fix broken link and wording
bc2e4bc [Andrew Or] Merge github.com:apache/incubator-spark into streaming-typos
d5515b4 [Andrew Or] TD's comments
767ef12 [Andrew Or] Fix broken links
8f4c731 [Andrew Or] Fix typos in programming guide
[SPARK-1090] improvement on spark_shell (help information, configure memory)

https://spark-project.atlassian.net/browse/SPARK-1090

spark-shell should print help information about parameters and should allow user to configure exe memory
there is no document about hot to set --cores/-c in spark-shell

and also

users should be able to set executor memory through command line options

In this PR I also check the format of the options passed by the user

Author: CodingCat <zhunansjtu@gmail.com>

Closes #599 from CodingCat/spark_shell_improve and squashes the following commits:

de5aa38 [CodingCat] add parameter to set driver memory
915cbf8 [CodingCat] improvement on spark_shell (help information, configure memory)
SPARK-1098: Minor cleanup of ClassTag usage in Java API

Our usage of fake ClassTags in this manner is probably not healthy, but I'm not sure if there's a better solution available, so I just cleaned up and documented the current one.

Author: Aaron Davidson <aaron@databricks.com>

Closes #604 from aarondav/master and squashes the following commits:

b398e89 [Aaron Davidson] SPARK-1098: Minor cleanup of ClassTag usage in Java API
Optimized imports

Optimized imports and arranged according to scala style guide @
https://cwiki.apache.org/confluence/display/SPARK/Spark+Code+Style+Guide#SparkCodeStyleGuide-Imports

Author: NirmalReddy <nirmal.reddy@imaginea.com>
Author: NirmalReddy <nirmal_reddy2000@yahoo.com>

Closes #613 from NirmalReddy/opt-imports and squashes the following commits:

578b4f5 [NirmalReddy] imported java.lang.Double as JDouble
a2cbcc5 [NirmalReddy] addressed the comments
776d664 [NirmalReddy] Optimized imports in core
Migrate Java code to Scala or move it to src/main/java

These classes can't be migrated:
  StorageLevels: impossible to create static fields in Scala
  JavaSparkContextVarargsWorkaround: incompatible varargs
  JavaAPISuite: should test Java APIs in pure Java (for sanity)