Feeds

Rss 2.0 Feeds for SciPy Central. This code generates the following types of feeds

1. `/feeds/` Where we observer 30 recent submissions 
2. `/feeds/<tag_name>/` we observe 30 recent submissions under `<tag_name>`
3. `/feeds/<entry_id>/<rev_id>/` feed for a particular entry - <slug> is ignored in the url. As in case of submissions urls, we used slug for the sake of search engines.
4. `/feeds/atom/` atom format of `/feeds/` 

All these links are placed in respective templates.
Example:

1. On homepage,we observe [1] on the right side bar and in the footer
2. We observer [2] on the right side bar while searching a tag `/item/tag/IPython/` (example)
3. We can observe [3] on the right side bar of submission page `/item/4/1/` (example)
4. [4] is just not shown on the template.. may be Rss is enough.