Consistent format for class objects in javascript

app/assets/javascripts/commit/file.js.coffee

@@ -4,4 +4,4 @@ class CommitFile
     if $('.image', file).length
       new ImageFile(file)
 
-this.CommitFile = CommitFile
\ No newline at end of file
+@CommitFile = CommitFile

app/assets/javascripts/commit/image-file.js.coffee

@@ -125,4 +125,4 @@ class ImageFile
       img.on 'load', =>
         callback.call(this, domImg.naturalWidth, domImg.naturalHeight)
 
-this.ImageFile = ImageFile
\ No newline at end of file
+@ImageFile = ImageFile