Added identity parameter to subscribe() call.
Added identity parameter to subscribe() call.

Needed when default authorization in insufficient.

apaprocki/blpapi-node,apaprocki/blpapi-node,bloomberg/blpapi-node,bloomberg/blpapi-node,jmptrader/blpapi-node,apaprocki/blpapi-node,jmptrader/blpapi-node,bloomberg/blpapi-node,jmptrader/blpapi-node