[html-formfu] How to remove the <span>..</span> for customized element

[Brian Cassidy]

Carl Franks wrote:
> ...but then on second thought, I decided it was a quite reasonable
> request to support without having to customise your templates.
> 
> So now if you do $field->container_tag(undef);
> - or "container_tag: ~" in yaml -
> it'll skip the span tag.

fireartist++

Container tags can be handy, but it's nice to be able to clean up the 
output.

-Brian