change target_tag_name of TagSynonym to target_tag (foreign key to Tag m...

...odel)


I find target_tag (as foreign key) is better than target_tag_name as you once mentioned.  

I wasn't and am not sure if submitting south migrations file is a good idea but its there.

(I'll create a tag index using haystack/solr anyway and thought having simpler DB schema is better here. and maybe for DB query as well)