Support segment/total_segments for scans

[mrkamel]

Hi,

it seems the segment/total_segments options can not be used yet from within dynamoid (right?), but i think this would be a really great addition to parallelize requests:

MyTable.with_segment(3, total_segments: 16).where(some_field: 'value').delete

What do you think? Any plans adding it? Would you be open for PRs regarding it?

[andrykonchin]

Hey. Agree, it may be useful. The proposed signature (with_segment(int, total_segments: int)) looks good.