add ability to reload comments after changing state

[PetrDlouhy]

Few changes that allowed me to reload comments for different object after page load (for usage in modal dialog). I don't know anything about React, so the code is rather hacky, and with the version 3.0 on the way I think we don't need to put much effort into polishing this. I am putting it here just to show how I solved #335.

I am reloading the comments with:

     $.getJSON(
         "/asset-comment/" + asset_id + "/",
         function(comments_props, textStatus, jqxhr) {
            comments_props_override = {
               allow_comments: true,
               allow_feedback: true,
               show_feedback: true,
               allow_flagging: true,
               polling_interval: 5000
            };
            window.commentBox.setState({props: Object.assign(comments_props, comments_props_override)});
            window.commentBox.reload_all();
        }
      );

Where on the /asset-comment/xxxx/ url is view that just returns JSON with the comments_props.