Code cleanup. Added comments.

src/Util/Callbackify.ts

@@ -1,5 +1,8 @@
 
-
+/**
+ * Helper function to convert callbacks into promises
+ * @param func 
+ */
 export default function callbackify(func: (...args: any[]) => Promise<any>): Function {
     return (...args: any[]) => {
         const onlyArgs: any[] = [];