let data-parsley attributes have preference over html5 attributes

the reason is that html5 attributes might be necessary for whatever
reason, but data-parsley-* attributes are only used for parsley
validation.

Example: a mobile oriented site might want to set an input's type to "number", so that the UA shows a numeric keyboard, but at the same "number" validation might not be desired.
add data-parsley-type="any" so that html5 type attribute can be overridden
if the type="number", get value by temporarily setting type to text

UAs return an empty string when getting the value of an invalid input of
type="number"