Newsletter signup

[ravage84]

The newsletter sign up on http://cakephp.org/ is implemented a bit lukewarm.

It would be nice to have a separate, linkable page for the newsletter sign up where I would also get some more info about the newsletter, e.g. what to expect from which newsletter.

Also, on the newsletter archive page a link to that mentioned sign up page at the top of the page would be better, since the archive list could get long after some time.