Issue #144 (Add last_modified to WSF_SKELETON_HANDLER)

it would be even better using EIS functionalities.such as

		note
			EIS: "name=Specification", "protocol=URI", "src=https://tools.ietf.org/html/rfc7232#section-2.2.1"

this way, EiffelStudio provides user friendly way to follow the link.

Note my comment is mainly for info