Use transclusion for status-button directive

Using transclusion allows for the directive to be set on an element
with non-trivial content and have that content nested inside the
status-button wrapper spans, but pre-bound to its lexical markup
scope.

Not sure we'll need it here, but I also wanted to see how one might
approximate 'replace' now that it's deprecated. The answer is by
not replacing but just adding the template you want after the passed
placeholder comment node.