fix(text): callback added in text

Author: ritz078

demo/index.html

@@ -95,7 +95,7 @@ <h1>Loading embed.js in a block</h1>
         console.log(data);
     });
 
-    x.text().then(function(data) {
+    x.text(function(data) {
         console.log(data)
     });
 

dist/embed.min.js

@@ -311,12 +311,8 @@ export default class EmbedJS {
 	 * returns the resulting string based on the input and the options passed by the user.
 	 * @return Promise
 	 */
-	text() {
-		return new Promise((resolve) => {
-			this.process().then(() => {
-				resolve(this.data)
-			})
-		})
+	text(callback) {
+		this.process().then((data)=> callback(data, this.input))
 	}
 
 	/**