[speech-to-text] New parameters to be added

New parameters has been added to Watson Speech-to-text service which needs to be added to Node SDK.

1. sad_module :1 or 2 (default = 1)
2. speech_begin_event: true or false (default false).

More details for these can be found at: https://cloud.ibm.com/apidocs/speech-to-text#recognize-request