[#1687] ticket:582 Add if_missing to OAuthConsumerToken.description
[#1687] ticket:582 Add if_missing to OAuthConsumerToken.description

Prevents /auth/oauth/ from raising errors about markdown_html being
absent (may happen when token created without description, e.g. in trac
importer)

apache/allura,lym/allura-git,apache/allura,heiths/allura,lym/allura-git,heiths/allura,heiths/allura,heiths/allura,lym/allura-git,apache/allura,heiths/allura,lym/allura-git,lym/allura-git,apache/allura,apache/allura