Support most used key types and all value types, support customized java serializer.

1. We need to support key types:
   • BooleanWritable
   • BytesWritable
   • ByteWritable
   • DoubleWritable
   • FloatWritable
   • IntWritable
   • LongWritable
   • NullWritable
   • Text
   • UTF8
   • VIntWritable
   • VLongWritable
   • HBase KeyValue….
   • Hive HiveKey…..

2. all value types.

3. Easy to use serialization framework.