Introducing the CSP Fixer

@devoncarew

Devon: sorry, a couple of unrelated trivial changes have crept in.

I should also add tests.

Also note that I deliberately exposed the feature only in the form of an explicit action. I didn't want to build it into the Bower install/update sequence or anything like that because it's too early and too risky.

> I think it's following the spec accurately. All these missing tags are actually implied for a "regular" HTML document.

exactly right. e.g. http://www.whatwg.org/specs/web-apps/current-work/multipage/syntax.html#the-before-html-insertion-mode

fwiw, I'm not opposed to adding flags to html5lib for non-standard behavior, but would prefer if the default values follow the spec.