drop htmlhint given htmllint gives us most of the coverage we need here

build/.htmlhintrc

@@ -1,17 +0,0 @@
-{
-  "alt-require": true,
-  "attr-lowercase": true,
-  "attr-no-duplication": true,
-  "attr-unsafe-chars": true,
-  "attr-value-double-quotes": true,
-  "doctype-first": true,
-  "doctype-html5": true,
-  "id-class-value": true,
-  "id-unique": true,
-  "space-tab-mixed-disabled": true,
-  "spec-char-escape": true,
-  "src-not-empty": true,
-  "tag-pair": true,
-  "tagname-lowercase": true,
-  "title-require": true
-}