Transparently support HEAD by making it use the GET action

Rather than returning a 405, as per the HTTP spec (RFC2616) 9.6:

    The HEAD method is identical to GET except that the server MUST NOT
    return a message-body in the response. The metainformation contained
    in the HTTP headers in response to a HEAD request SHOULD be
    identical to the information sent in response to a GET request. This
    method can be used for obtaining metainformation about the entity
    implied by the request without transferring the entity-body itself.
    This method is often used for testing hypertext links for validity,
    accessibility, and recent modification.

The HEAD method will default to the GET action on the controller, unless
specifically overriden as part of a new route.
Clean up some sloppy comments