Convert textfield component render method

[randallknutson]

All components need to use react-native compatible components.

See https://github.com/formio/react-native-formio/blob/master/src/components/FormComponents/mixins/inputMixin.jsx#L109-L112 https://github.com/formio/react-native-formio/blob/master/src/components/FormComponents/mixins/multiMixin.jsx#L31-L82 https://github.com/formio/react-native-formio/blob/master/src/components/FormComponents/mixins/valueMixin.jsx#L310-L314

To test this, set up a simple form with just a textfield in form.io and attempt to display it in react-native.