deviantart: remove obsolete image sample rewrite rules.

Remove rewrite rules for these types of sample urls:

* http://th00.deviantart.net/fs71/PRE/f/2014/065/3/b/goruto_by_xyelkiltrox-d797tit.png
* http://th04.deviantart.net/fs70/300W/f/2009/364/4/d/Alphes_Mimic___Rika_by_Juriesute.png

These URLs aren't served to users any more, and just stripping out "PRE"
or "200H" isn't sufficient to get the full size image. In general, an
api call is required to find the full size image url.

app/logical/sources/strategies/deviant_art.rb

@@ -18,17 +18,6 @@ module Sources
       end
 
       def image_urls
-        # normalize thumbnails
-        if url =~ %r{^(https?://(?:fc|th)\d{2}\.deviantart\.net/.+?/)200H/}
-          match = $1
-          return [url.sub(match + "200H/", match)]
-        end
-
-        if url =~ %r{^(https?://(?:fc|th)\d{2}\.deviantart\.net/.+?/)PRE/}
-          match = $1
-          return [url.sub(match + "PRE/", match)]
-        end
-
         # return direct links
         if url =~ ATTRIBUTED_ASSET || url =~ ASSET
           return [url]