Issue #362 - Simple comments - Changes based on feedback recieved from #mediagoblin

*   `db.models` - Removed `MediaEntry.get_comments()` and replaced it with a helper
    which just returns a cursor for the comments query
*   `media.html` - Added `{% set comment_author = comment.author() %}`
*   `user_pages.views` - media_home() now passes `MediaEntry.get_comments()`
    directly to `Pagination`, handles pagination for comments.
    *   Added `MEDIA_COMMENTS_PER_PAGE` to define the number of comments per page
        in the `media_home()` view.

mediagoblin/user_pages/views.py

@@ -82,17 +82,19 @@ def user_gallery(request, page):
          'media_entries': media_entries,
          'pagination': pagination})
 
+MEDIA_COMMENTS_PER_PAGE = 50
 
 @get_user_media_entry
 @uses_pagination
-def media_home(request, media, **kwargs):
+def media_home(request, media, page, **kwargs):
     """
     'Homepage' of a MediaEntry()
     """
 
-    comment_form = user_forms.MediaCommentForm(request.POST)
+    pagination = Pagination(page, media.get_comments(), MEDIA_COMMENTS_PER_PAGE)
+    comments = pagination()
 
-    (comments, pagination) = media.get_comments(kwargs.get('page'))
+    comment_form = user_forms.MediaCommentForm(request.POST)
 
     return render_to_response(
         request,