Add IBM's Text to Speech API

The Text to Speech service processes text and natural language to generate synthesized audio output complete with appropriate cadence and intonation.
More info on https://console.bluemix.net/catalog/services/text-to-speech

README.md

@@ -228,6 +228,7 @@ API | Description | Auth | HTTPS | CORS |
 | [GitHub](https://developer.github.com/v3/) | Make use of GitHub repositories, code and user info programmatically | `OAuth` | Yes | Yes |
 | [Gitlab](https://docs.gitlab.com/ee/api/) | Automate GitLab interaction programmatically | `OAuth` | Yes | Unknown |
 | [Gitter](https://github.com/gitterHQ/docs) | Chat for GitHub | `OAuth` | Yes | Unknown |
+| [IBM® Text to Speech](https://console.bluemix.net/docs/services/text-to-speech/getting-started.html#gettingStarted) | Convert text to speech | `OAuth` | Yes | Yes |
 | [HTTP2.Pro](https://http2.pro/doc/api) | Test endpoints for client and server HTTP/2 protocol support | No | Yes | Unknown |
 | [import.io](http://api.docs.import.io/) | Retrieve structured data from a website or RSS feed | `apiKey` | Yes | Unknown |
 | [IPify](https://www.ipify.org/) | A simple IP Address API | No | Yes | Unknown |