Ensure use_record_as_seed for same records

[sihyeonn]

use_record_as_seed cannot ensure same result for same record but different order of keys when use_entire_record. To ensure use_record_as_seed with use_entire_record, I changed code as using sorted keys to make seed.

Signed-off-by: Sihyeon Jang uneedsihyeon@gmail.com

DESCRIPTION HERE

(check all that apply)

• [ ] tests added
• [x] tests passing
• [x] README updated (if needed)
• [x] README Table of Contents updated (if needed)
• [x] History.md and version in gemspec are untouched
• [ ] backward compatible
• [ ] feature works in elasticsearch_dynamic (not required but recommended)