preserve attribute name casing in builds

[thephilgray]

update htmltidy options.

1. (required) add inputXml: true

2. (possibly) remove doctype "xhtml" is not a recognized value for "doctype" see: http://api.html-tidy.org/tidy/quickref_5.6.0.html#doctype

3. (possibly) remove outputXhtml: true. I'm not sure if this is actually having any effect.

updated object should look like this:

{
          inputXml: true,
          outputXhtml: true,
          indent: "auto",
          wrap: 120,
          "wrap-attributes": false,
          "drop-empty-elements": "no"
}