on submission, use inline error messaging instead of message queue

- the function that converts the user's tag string into a list of
  tags now accepts a string, but the media submit view was still
  submitting the request object, like we were going to add any
  errors to the session. Now the submit view passes the tag string

mediagoblin/submit/views.py

@@ -62,7 +62,7 @@ def submit_start(request):
             entry['uploader'] = request.user['_id']
 
             # Process the user's folksonomy "tags"
-            entry['tags'] = convert_to_tag_list(request)
+            entry['tags'] = convert_to_tag_list(request.POST.get('tags'))
 
             # Save, just so we can get the entry id for the sake of using
             # it to generate the file path