Public review comment: Support for markup head attributes

Currently portlets have no means in WSRP to set attributes that should 
appear in the head section of the markup returned to the client, like 
meta tags for search engines or the page title.

Proposal:
Introduce a markupHeadAttributes field in response structures. The 
consumer would be encouraged to forward these attributes in the head 
section of the markup document to the client if they don't conflict with 
other attributes set by the consumer (e.g. only one page title is allowed).

Stefan