Merge pull request #10 from dominicbarnes/small_enhancements

Some small enhancements
0.9.0

* change `#validator` to be chainable
* change `required` validator to handle non-strings
* remove `novalidate` attribute from forms
* call validators with `Field` as context
adding reference to parent validator in each field, shortening signature
slight verbage change to History
adding an 'equal' validation test