SPARK-1242 Add aggregate to python rdd

Author: Holden Karau <holden@pigscanfly.ca>

Closes #139 from holdenk/add_aggregate_to_python_api and squashes the following commits:

0f39ae3 [Holden Karau] Merge in master
4879c75 [Holden Karau] CR feedback, fix issue with empty RDDs in aggregate
70b4724 [Holden Karau] Style fixes from code review
96b047b [Holden Karau] Add aggregate to python rdd
Call correct stop().

Oopsie in #504.

Author: Aaron Davidson <aaron@databricks.com>

Closes #527 from aarondav/stop and squashes the following commits:

8d1446a [Aaron Davidson] Call correct stop().
SPARK-1607. Replace octal literals, removed in Scala 2.11, with hex literals

Octal literals like "0700" are deprecated in Scala 2.10, generating a warning. They have been removed entirely in 2.11. See https://issues.scala-lang.org/browse/SI-7618

This change simply replaces two uses of octals with hex literals, which seemed the next-best representation since they express a bit mask (file permission in particular)

Author: Sean Owen <sowen@cloudera.com>

Closes #529 from srowen/SPARK-1607 and squashes the following commits:

1ee0e67 [Sean Owen] Use Integer.parseInt(...,8) for octal literal instead of hex equivalent
0102f3d [Sean Owen] Replace octal literals, removed in Scala 2.11, with hex literals
SPARK-1619 Launch spark-shell with spark-submit

This simplifies the shell a bunch and passes all arguments through to spark-submit.

There is a tiny incompatibility from 0.9.1 which is that you can't put `-c` _or_ `--cores`, only `--cores`. However, spark-submit will give a good error message in this case, I don't think many people used this, and it's a trivial change for users.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #542 from pwendell/spark-shell and squashes the following commits:

9eb3e6f [Patrick Wendell] Updating Spark docs
b552459 [Patrick Wendell] Andrew's feedback
97720fa [Patrick Wendell] Review feedback
aa2900b [Patrick Wendell] SPARK-1619 Launch spark-shell with spark-submit