Handle top-level use of tpl-arg syntax {{{foo|bar}}}

* Template arg syntax {{{foo|bar}}} is normally encountered in
  template context.  However, occasionally, they are encountered
  outside templates (ex: when templates are rendered as a normal
  page).  In this context, template arg syntax should be
  appropriately wrapped so that it gets RTed properly.

* This patch wraps such uses with "mw:Object/Param" RDF attributes
  and regular template encapsulation code and serialization code
  takes care of the rest (because of the common mw:Object/ prefix
  that they look out for).

* Fixes RTing of {{{foo|'''it'' plain ''bold''}}}

* Parser Tests results:
  - 2 more wt2wt tests passing.
  - One wt2html test now failing because
    of the extra span -- we could either whitelist this or fix
	our wrapping/normalization to detect this.
  - 35 more selser tests passing with my changes file.

* Eliminates some RT errors from
  en:Wikipedia:Categories_for_discussion/Log/2007_April_30

Change-Id: I1efce232f87551eb557fb0995a0924e6c41b21e8