SPARK-1173. Improve scala streaming docs.

Clarify imports to add implicit conversions to DStream and
fix other small typos in the streaming intro documentation.

Tested by inspecting output via a local jekyll server, c&p'ing the scala commands into a spark terminal.

Author: Aaron Kimball <aaron@magnify.io>

Closes #64 from kimballa/spark-1173-streaming-docs and squashes the following commits:

6fbff0e [Aaron Kimball] SPARK-1173. Improve scala streaming docs.
SPARK-1173. (#2) Fix typo in Java streaming example.

Companion commit to pull request #64, fix the typo on the Java side of the docs.

Author: Aaron Kimball <aaron@magnify.io>

Closes #65 from kimballa/spark-1173-java-doc-update and squashes the following commits:

8ce11d3 [Aaron Kimball] SPARK-1173. (#2) Fix typo in Java streaming example.
Removed accidentally checked in comment

It looks like this comment was added a while ago by @mridulm as part of a merge and was accidentally checked in.  We should remove it.

Author: Kay Ousterhout <kayousterhout@gmail.com>

Closes #61 from kayousterhout/remove_comment and squashes the following commits:

0b2b3f2 [Kay Ousterhout] Removed accidentally checked in comment
update proportion of memory

The default value of "spark.storage.memoryFraction" has been changed from 0.66 to 0.6 . So it should be 60% of the memory to cache while 40% used for task execution.

Author: Chen Chao <crazyjvm@gmail.com>

Closes #66 from CrazyJvm/master and squashes the following commits:

0f84d86 [Chen Chao] update proportion of memory
Remove the remoteFetchTime metric.

This metric is confusing: it adds up all of the time to fetch
shuffle inputs, but fetches often happen in parallel, so
remoteFetchTime can be much longer than the task execution time.

@squito it looks like you added this metric -- do you have a use case for it?

cc @shivaram -- I know you've looked at the shuffle performance a lot so chime in here if this metric has turned out to be useful for you!

Author: Kay Ousterhout <kayousterhout@gmail.com>

Closes #62 from kayousterhout/remove_fetch_variable and squashes the following commits:

43341eb [Kay Ousterhout] Remote the remoteFetchTime metric.
Added a unit test for PairRDDFunctions.lookup

Lookup didn't have a unit test. Added two tests, one for with a partitioner, and one for without.

Author: Bryn Keller <bryn.keller@intel.com>

Closes #36 from xoltar/lookup and squashes the following commits:

3bc0d44 [Bryn Keller] Added a unit test for PairRDDFunctions.lookup
SPARK-1158: Fix flaky RateLimitedOutputStreamSuite.

There was actually a problem with the RateLimitedOutputStream implementation where the first second doesn't write anything because of integer rounding.

So RateLimitedOutputStream was overly aggressive in throttling.

Author: Reynold Xin <rxin@apache.org>

Closes #55 from rxin/ratelimitest and squashes the following commits:

52ce1b7 [Reynold Xin] SPARK-1158: Fix flaky RateLimitedOutputStreamSuite.
Remove broken/unused Connection.getChunkFIFO method.

This method appears to be broken -- since it never removes
anything from messages, and it adds new messages to it,
the while loop is an infinite loop.  The method also does not appear
to have ever been used since the code was added in 2012, so
this commit removes it.

cc @mateiz who originally added this method in case there's a reason it should be here! (https://github.com/apache/spark/commit/63051dd2bcc4bf09d413ff7cf89a37967edc33ba)

Author: Kay Ousterhout <kayousterhout@gmail.com>

Closes #69 from kayousterhout/remove_get_fifo and squashes the following commits:

053bc59 [Kay Ousterhout] Remove broken/unused Connection.getChunkFIFO method.
[java8API] SPARK-964 Investigate the potential for using JDK 8 lambda expressions for the Java/Scala APIs

Author: Prashant Sharma <prashant.s@imaginea.com>
Author: Patrick Wendell <pwendell@gmail.com>

Closes #17 from ScrapCodes/java8-lambdas and squashes the following commits:

95850e6 [Patrick Wendell] Some doc improvements and build changes to the Java 8 patch.
85a954e [Prashant Sharma] Nit. import orderings.
673f7ac [Prashant Sharma] Added support for -java-home as well
80a13e8 [Prashant Sharma] Used fake class tag syntax
26eb3f6 [Prashant Sharma] Patrick's comments on PR.
35d8d79 [Prashant Sharma] Specified java 8 building in the docs
31d4cd6 [Prashant Sharma] Maven build to support -Pjava8-tests flag.
4ab87d3 [Prashant Sharma] Review feedback on the pr
c33dc2c [Prashant Sharma] SPARK-964, Java 8 API Support.
Move java home check after process args.