feat(formManager): support nested forms

Changes made to the formManager:
- The form data object can now live outside the form object.
- Variables inside the form object now use the $ prefix, i.e. are $tooltip,
  $focus and $failed.
- formObj.$data is watched for changes if no other data object name is given.
- fail() looks for invalid fields in nested forms, if they have a name=""
  attribute.