Add Firefox WebIDL Javascript exploit.

Also removes an incorrect reference from another FF exploit.
Fix typo in PR #3712

Fixes the typo pointed out in
rapid7#3712#discussion_r16750554

Derp
Get the disclosure date right.
Land fix for #3712 typo
Rename exploit module.
Land #3714 - Firefox 22-27 WebIDL Privileged Javascript Injection