Also minify CSPs (fixes #947)

[ENT8R]

I hope everything is OK. (I didn't take a look into the whole codebase and don't know if this would be the right place to add it...)

[XhmikosR]

Please fix the test failures and rebase against upstream/master.

[ENT8R]

I fixed the indentation issues with fa17d5c
Github IDE screwed something up there... Sorry for that.

[XhmikosR]

Looks good now. One thing I don't know though because I haven't dug deep into the codebase myself either, is if we need to lowercase tags, their names and/or their values before the comparisons.

[alexlamsl]

HTTP headers are case insensitive, plus the follow two MDN links listed <meta> usage using different case schemes:
https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta

So I'd say we need to do a lower case comparison here. Also, can we get a test case or two for this new feature?

Just add a new section at the end of tests/minifier.js like so:

QUnit.test('minify Content-Security-Policy', function(assert) {
  assert.equal(minify(...), ...);
  ...
});

[ENT8R]

So now there are also some test cases and a case insensitive check with e066084

[alexlamsl]

Changes LGTM − now if I can just figure out how to get the Cursed Integration job to start for this PR...