Add 'dom-form-value' for Y.DOM.formToObject(el)

Does essentially what io._serialize does, except without the
encodeURIComponent() calls on every string. And doesn't rely on IO. IO should
rely on this, most likely.
Build 'dom-form-values'
Rebuild yui with Loader data for dom-form-values
Lowercase field.tagName and field.type
Build dom-form-values
Reset value in elements iteration to avoid bleedover
Build dom-form-values