MOBILE-478 Add support for the File API (Node.js)

https://tracker.moodle.org/browse/MOBILE-478
 MOBILE-478 Fixing style issues

Indentation (due to bad copy & paste)
Hardcoded file name, it was an error due some test I did, I changed it
for the correct var
Merge pull request #23 from moodlehq/MOBILE-478

MOBILE-478 Add support for the File API (Node.js)