Allow to add connection with through data for HasManyThrough relation

Signed-off-by: Clark Wang <clark.wangs@gmail.com>
add jsdoc and fix add data to referencesMany.add

Signed-off-by: Clark Wang <clark.wangs@gmail.com>
revert change to ReferencesMany.prototype.add

Signed-off-by: Clark Wang <clark.wangs@gmail.com>
Revert leading spaces
revert eof
revert eof
Merge pull request #275 from clarkorz/feature/add-with-through-data

Allow to add connection with through data for HasManyThrough relation