Added support to choose either atom or rss for the "/feed" format.
Added support for feed format view to feed aggregation.
Use proper content type for RSS and ATOM response.
For feed aggregation use `?view=feed` or `?view=feed.atom` or `?view=feed.rss`
Improved sized feed view.
Use site name for recent changes feed title.
Better name for node feeds (include the site name).
Use current date when a feed aggregation is converted to a new feed, to set the last build date.
Fixed category filter per feed location for the feed aggregation module.
Fixed authentication module, where a potential case (but not probable) had no response content.
Cosmetic and minor changes on messaging module.