Assign the correct form to self.formController.form
Add an example use of FXFormFieldValueTransformer to the BaseExample

Note that this PR depends on the bugfix in PR #17
Merge pull request #17 from bartvandendriessche/bugfix/assign_correct_form_to_subcontrollers

Assign the correct form to self.formController.form
Improved setter logic for form
Merge branch 'master' of https://github.com/nicklockwood/FXForms
Merge pull request #18 from bartvandendriessche/example/NSValueTransformer

Add an example use of FXFormFieldValueTransformer to the BaseExample
Merge branch 'master' of https://github.com/nicklockwood/FXForms
Added FXFormFieldValueTransformer example
Added missing setter case logic