The very first thing you should do with any issue like this is to check your browser console for errors.
Judging by what you've said, you're probably using a Heroku domain name. Heroku domains are only accessible via https, and Chrome won't load non-https resources on https urls, so you need to make sure all your resources are https.
In your case, your angular and boostrap libraries are not being included via https. Luckily for you, these CDNs support https, so you just need to change your URLs to this:
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script> <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.3/angular.min.js"></script> Chances are your browser console is reporting something like this:
Mixed Content: The page at 'xxx' was loaded over HTTPS, but requested an insecure script 'http://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js'. This request has been blocked; the content must be served over HTTPS. Which is why you should always check your console for errors. Most of the time, it'll tell you exactly what the issue is.
Also, your app.js path looks wrong. /../app.js is not a valid URL. Without seeing your file structure, it's hard to say what this should actually be, but if the angular seed project is anything to go by, it should just be something like this:
<script type="text/javascript" src="app.js"></script> Again, if your URL is incorrect, the console will tell you.