Attempt at implementing file upload progress

This is a rudimentary attempt at implementing file upload progress handling.  However, I do not have a setup currently to test file uploading with Angular, so if someone else is able to get to it and report their findings when using this before I am able to create a setup, it would be much appreciated.

I want to generate feedback before I write tests for this new feature implementation, whether this is the right way to go.

To use this, one would do 

    $http.post('/file/upload/url', formData)
         .then(null, null, function(e) { 
           if (e.lengthComputable) console.log(e.loaded / e.total); 
         });