CONN-86: wall owner fix - broken comments_index row with id equal 0 can cause wrong wall owner detecion
CONN-86: wall comments index - checking for empty values
CONN-86: wall comments index bug - adding unit test for db rows with empty comment_id
CONN-86: wall comments index - prevent multiple call to newFromId when comments_index row is missing
Merge pull request #2419 from Wikia/CONN-86-wall-comments-index-fix

Conn 86 wall comments index fix