Implement DataBlock backed by byte[]

[alexrobin]

A byte array backed DataBlock has the following advantages:

1. Can be serialized as-is in storage.
2. Lower memory footprint with less objects and object references
3. Fields can be quickly accessed once an indexer is created from the SWE component structure
4. Can always be converted to another type of DataBlock

Note that it could be implemented for both binary and CSV encoded byte[].