Add field articles on articles link
Add field articles on articles link admin
Create migration articles link, add field link articles
Fix migration, custom migration user Django 1.5 on 0004_auto__add_field_link_articles.py
refs: http://www.oppsproject.org/en/latest/develop.html#south-migrations
add rule link select article, on articles link
try long slug exist, on OppsDetail (articles views)