[SPARK-1186] : Enrich the Spark Shell to support additional arguments.

Enrich the Spark Shell functionality to support the following options.

```
Usage: spark-shell [OPTIONS]

OPTIONS:
    -h  --help              : Print this help information.
    -c  --cores             : The maximum number of cores to be used by the Spark Shell.
    -em --executor-memory   : The memory used by each executor of the Spark Shell, the number
                              is followed by m for megabytes or g for gigabytes, e.g. "1g".
    -dm --driver-memory     : The memory used by the Spark Shell, the number is followed
                              by m for megabytes or g for gigabytes, e.g. "1g".
    -m  --master            : A full string that describes the Spark Master, defaults to "local"
                              e.g. "spark://localhost:7077".
    --log-conf              : Enables logging of the supplied SparkConf as INFO at start of the
                              Spark Context.

e.g.
    spark-shell -m spark://localhost:7077 -c 4 -dm 512m -em 2g
```

**Note**: this commit reflects the changes applied to _master_ based on [5d98cfc1].

[ticket: SPARK-1186] : Enrich the Spark Shell to support additional arguments.
                        https://spark-project.atlassian.net/browse/SPARK-1186

Author      : bernardo.gomezpalcio@gmail.com

Author: Bernardo Gomez Palacio <bernardo.gomezpalacio@gmail.com>

Closes #116 from berngp/feature/enrich-spark-shell and squashes the following commits:

c5f455f [Bernardo Gomez Palacio] [SPARK-1186] : Enrich the Spark Shell to support additional arguments.