Fix some spec failures and warnings
Remove 'quote' attribute from citation group contextt
Change reference/citation_groups to be a list of indexes to avoid duplication
Remove 'mentions' and 'sections' from reference object (Can be easily derived)
Move word_count to root instead of paper/bibliographic object
Remove 'zero_mentions' from reference object
Rename 'paper' root object to 'bibliographic' to match terminology and usage elsewhere