Change to use SSL when calling Conversations API

[aotarola]

It looks like SSL is required when sending POSt request to Conversations API, otherwise the following error returns:

{ 
  "error": { 
     "code": 403,
     "message": "SSL is required to perform this operation.",
     "status": "PERMISSION_DENIED" 
  } 
}

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[aotarola]

I signed it!

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CLAs look good, thanks!