workaround double-loading of "name", resulting in it being used for the value as well as the field name and ID.
Now, it uses "field" instead of "name". Also added placeholder and label attributes.
Example:
                    "extraSignUpFields": [{
                            "field": "name",
                            "name":"This Will Be The Initial Value",
                            "label": "Full Name",
                            "placeholder": "John Doe",
                            "type": "text",
                            "required": true
                        }]
Pass on change of fieldname from "name" to "field".
make tinytest tests pass for previous changes.
Merge pull request #209 from cunneen/master

Allow extraSignupField "name".