Bug 1080409 - Remove meta tags not in the spec

* X-UA-Compatible is an IE-ism
* cache-control is ignored in many browsers and HTTP headers should be
used instead:
https://www.mnot.net/cache_docs/#META
Bug 1080409 - Simplify charset meta tag & add to other pages

The longer format is not necessary:
https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Obsolete_things_to_avoid#%3Cmeta%3E_element_and_charset_attribute
Bug 1080409 - Remove unnecessary closing slash from void tags
Bug 1080409 - Set a page title prior to Angular calculating it

This fixes the validation error as well as covering search engines &
the disabled javascript case.
Bug 1080409 - HTML encode the ampersand on the help page
Bug 1080409 - Make markup whitespace more consistent
Bug 1080419 - Add an optional grunt HTML validator

Run using |grunt htmlangular|