Fix "unknown user" when creating an annotation

I would like to be able to see the correct nuxeo user's name when making annotation in ARender.

Current behaviour:
Currently, the ARender UI is displaying "unknown user", during annotating, regardless the user that is making the annotation.

Acceptance Criteria:

• When a nuxeo user "Smith" is making an annotation in ARender, we want it's name displayed on the annotation window that he is making.