Merge pull request #219 from Eyesonly88/master

Fixes compile error when getting packaged by metro

src/index.js

   lastCapturedURI: ?string;
 
   resolveFirstLayout: (layout: Object) => void;
-  firstLayoutPromise = new Promise<void>(resolve => {
+  firstLayoutPromise = new Promise(resolve => {
     this.resolveFirstLayout = resolve;
   });