Synthesize method does not honor access_token from IAM API Key

[jeancarl]

In SDK v.0.36 with Firefox 60.3.0esr (64-bit), using the new IAM API Key authentication for Text to Speech, the synthesize method filters out the access_token parameter.

var params = {
  text: "Hello",
  voice: "en-US_MichaelVoice",
  access_token: "<ACCESS_TOKEN>"
};

stream = WatsonSpeech.TextToSpeech.synthesize(params);

The requested URI resource doesn't include this access token and the watson-token parameter is undefined, returning a CORS error.

https://stream.watsonplatform.net/text-to-speech/api/v1/synthesize?voice=en-US_MichaelVoice&text=Hello&watson-token=**undefined**

---

There should also be a check that token parameter is defined, given it's either token or access_token.

module.exports = function synthesize(options) {
  if (!options || (!options.token && !options.access_token)) {
    throw new Error('Watson TextToSpeech: missing required parameter: options.token (CF) or options.access_token (RC)');
  }
  options['watson-token'] = options.token;
  delete options.token;
  var audio = options.element || new Audio();

Checklist

• npm test passes (tip: npm run autofix can correct most style issues)

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[germanattanasio]

👍 Thanks for the PR @jeancarl.

@dpopp07 is currently maintaining this repo so I would like him to look at this too.

[dpopp07]

Looks good 👍

[watson-github-bot]

🎉 This PR is included in version 0.35.2 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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