votingAPI integration in d7 version requires minor changes

VotingAPI for drupal 7 changes some of the key names in the array structures passed to hook_votingapi_insert and hook_votingapi_delete. Where before you had 'content_type' and 'content_id' it now uses 'entity_type' and 'entity_id'.

Attached patch fixes this and at the same time also updates the query in _expire_votingapi() to use DBTNG and to use the new table name for comments ({comments} d6 -> {comment} d7).