[SPARK-1250] Fixed misleading comments in bin/pyspark, bin/spark-class

Fixed a couple of misleading comments in bin/pyspark and bin/spark-class. The comments make it seem like the script is looking for the Scala installation when in fact it is looking for Spark.

Author: Sumedh Mungee <smungee@gmail.com>

Closes #843 from smungee/spark-1250-fix-comments and squashes the following commits:

26870f3 [Sumedh Mungee] [SPARK-1250] Fixed misleading comments in bin/pyspark and bin/spark-class

(cherry picked from commit 6e337380fc47071fc7fb28d744e8209c729fe1e9)
Signed-off-by: Reynold Xin <rxin@apache.org>
[Docs] Correct example of creating a new SparkConf

The example code on the configuration page currently does not compile.

Author: Andrew Or <andrewor14@gmail.com>

Closes #842 from andrewor14/conf-docs and squashes the following commits:

aabff57 [Andrew Or] Correct example of creating a new SparkConf

(cherry picked from commit 1014668f2727863fe46f9c75201ee459d093bf0c)
Signed-off-by: Reynold Xin <rxin@apache.org>
[Minor] Move JdbcRDDSuite to the correct package

It was in the wrong package

Author: Andrew Or <andrewor14@gmail.com>

Closes #839 from andrewor14/jdbc-suite and squashes the following commits:

f948c5a [Andrew Or] cache -> cache()
b215279 [Andrew Or] Move JdbcRDDSuite to the correct package

(cherry picked from commit 7c79ef7d43de258ad9a5de15c590132bd78ce8dd)
Signed-off-by: Reynold Xin <rxin@apache.org>