Updated the js library to the faster loading one recommended by intercom

From the intercom website:

Faster loading Intercom javascript

We now serve the Intercom javascript from a CDN. This means faster load times for your users, no matter where in the world they live.
To take advantage, change your script tag from using https://api.intercom.io/api/js/library.js tohttps://static.intercomcdn.com/intercom.v1.js
The old one will continue to work, so don't worry if you can't make this change immediately.
If you're using our intercom-rails gem, then the latest version will do this for you.
Merge pull request #2 from dhrp/master

Update javascript library to use faster loading one.