[Feature Request] Binary type support

[tomykaira]

I am trying to handle msgpack encoded data with Embulk.
#121 mentions about binary type, but there are no progress.

Because I can control both input and output plugin, I consider Base64 encoding, but it is not simple solution and not applicable for all cases.
It would be great if embulk natively supports binary data type.

[toyama0919]

+1

some use case,

• Image recognition(deep learning)
• Image converter(like Imagemagick)

It is easy to do a little on Embulk.

[frsyuki]

Sounds good idea 👍
Similar to JSON type support, we'll also need toolset around binary columns such as:

• string conversion: base64/hex column encoder/decoder
• compression: gzip/lz4/snappy column encoder/decoder
• hash: md5/sha1/sha2 column encoder/decoder