[streaming][SPARK-1578] Removed requirement for TTL in StreamingContext.

Since shuffles and RDDs that are out of context are automatically cleaned by Spark core (using ContextCleaner) there is no need for setting the cleaner TTL while creating a StreamingContext.

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes #491 from tdas/ttl-fix and squashes the following commits:

cf01dc7 [Tathagata Das] Removed requirement for TTL in StreamingContext.
(cherry picked from commit f3d19a9f1a4e38ff9fb5bf78e04ed5d321219bf6)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>
[FIX: SPARK-1376] use --arg instead of --args in SparkSubmit to avoid warning messages

Even if users use `--arg`, `SparkSubmit` still uses `--args` for child args internally, which triggers a warning message that may confuse users:

~~~
--args is deprecated. Use --arg instead.
~~~

@sryza Does it look good to you?

Author: Xiangrui Meng <meng@databricks.com>

Closes #485 from mengxr/submit-arg and squashes the following commits:

5e1b9fe [Xiangrui Meng] update test
cebbeb7 [Xiangrui Meng] use --arg instead of --args in SparkSubmit to avoid warning messages
(cherry picked from commit 662c860ebcec5565493a7dff4812e6b7a37b1d7d)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>
SPARK-1562 Fix visibility / annotation of Spark SQL APIs

Author: Michael Armbrust <michael@databricks.com>

Closes #489 from marmbrus/sqlDocFixes and squashes the following commits:

acee4f3 [Michael Armbrust] Fix visibility / annotation of Spark SQL APIs
(cherry picked from commit aa77f8a6a604efe0d02bc8412b3f1ba3903b7a57)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>