Support Salmon for cross-site commenting and notification

[eschnou]

The salmon protocol enable comments to flow across sites. For example, a user could syndicate his storytlr feed in Google Buzz, while having all comments displayed on his storytlr page. When someone comments on Buzz, storytlr receives a notification of the comment via Salmon.

Salmon can also be used for cross-domain mentions, thus enabling a kind of 'federated wall', enabling a storytlr user to receive message from others on his wall (which could be another page). This is another step in making storytlr a good citizen of the federated social web.