feat(TTS): add tts plugin (#431)

* Initial Pass at TTS

* Rename and fix index

* Remove unnecessary window in reference

closes #311

src/plugins/text-to-speech.ts

@@ -0,0 +1,47 @@
+import {Plugin, Cordova} from './plugin';
+
+export interface TTSOptions {
+    /** text to speak */
+    text: string;
+    /** a string like 'en-US', 'zh-CN', etc */
+    locale?: string;
+    /** speed rate, 0 ~ 1 */
+    rate?: number;
+}
+
+/**
+ * @name TTS
+ * @description
+ * Text to Speech plugin
+ *
+ * @usage
+ * ```
+ * import {TTS} from 'ionic-native';
+ *
+ * TTS.speak('Hello World')
+ *   .then(() => console.log('Success'))
+ *   .catch((reason: any) => console.log(reason));
+ *
+ * ```
+ */
+@Plugin({
+  plugin: 'cordova-plugin-tts',
+  pluginRef: 'TTS',
+  repo: 'https://github.com/vilic/cordova-plugin-tts'
+})
+export class TextToSpeech {
+
+  /**
+   * This function speaks
+   * @param options {string | TTSOptions} Text to speak or TTSOptions
+   * @return {Promise<any>} Returns a promise that resolves when the speaking finishes
+   */
+  @Cordova({
+    successIndex: 1,
+    errorIndex: 2
+  })
+  static speak(options: string | TTSOptions): Promise<any> {
+    return;
+  }
+
+}