Fetch source data: list Danbooru artist tag; elim duplicated code.

* In the `Fetch source data` box, list the Danbooru artist tag(s) that
  were found beside the artist name.

* Unify `Fetch source data` code that was duplicated between the
  uploads page and the post show page.

app/assets/stylesheets/specific/uploads.scss

@@ -26,23 +26,6 @@ div#c-uploads {
       display: block;
     }
 
-    div#source-info {
-      margin: 1em 0;
-      padding: 1em;
-      border: 1px solid gray;
-      min-height: 5em;
-
-      p {
-        margin: 0;
-      }
-
-      ul {
-        a {
-          margin-right: 1em;
-        }
-      }
-    }
-
     div.field_with_errors {
       display: inline;
     }