[wp-docs] Hardening WordPress

[John Blackbourn]

I've just saved a fairly large change to the Hardening WordPress page [1].

I've basically cleaned the information that was there. Grammar and
presentation has been improved, some areas have been brought up to
date, and a couple of redundant sections have been removed. Some areas
have taken cues from the discussion page.

Any problems with the page, do let me know.

John

[1] http://codex.wordpress.org/Hardening_WordPress