Form not saving templateData when passed as an option

while `Form.render` includes the line
```js
var $form = $($.trim(this.template(_.result(this, 'templateData'))));
```
`Form.initialize` does not save `templateData` when passed as an option. This means a forms `templateData` property must be set separately before calling `Form.render`.

This pull request updates `Form.initialize` to save `templateData` when passed as an option as is currently done with options `model`, `data` and `idPrefix`.