[SPARK-2024] Adding key converter for hbase_inputformat.py
[SPARK-2024] Making Converter result type covariant
[SPARK-2024] Adding HBase output converter example
[SPARK-2024] Updates to TestInputFormat
[SPARK-2024] Adding standalone tests
[SPARK-2024] Style update
[SPARK-2024] Adding negative tests
[SPARK-2024] Adding a note for arrays
[SPARK-2024] Adding Cassandra output format example
[SPARK-2024] doc update
[SPARK-2024] API doc update
[SPARK-2024] more API doc update
[SPARK-2024] codecClass -> compressionCodecClass
[SPARK-2024] more API doc update
[SPARK-2024] more doc update
[SPARK-2024] fixing BytesWritable
[SPARK-2024] update programming guide