News expire 15 days after creation, fixes #276.
Using mibe/FeedWriter for Atom/RSS feeds.
FeedWriter code slightly modified to use it with limonade
- using 'return' instead of 'echo'
- using Limonade's send_header instead of PHP's builtin header()
Using ES5-Shim for ES5 Polyfills
ES5-Shim added to bundled scripts
fixed send_header call & FeedWriter#generateFeed
cursus & course Atom/RSS feeds added, fixes #274