Add object-role map and subject-role map requests.

"Describe/detail/explain/get what subject can do"
"Describe/detail/explain/get who can act [on object]"
Merge branch 'maps' of https://github.com/danmactough/node-relations into danmactough-maps

Conflicts:
	parser.js
	test/common.js
forward port maps feature
Merge branch 'danmactough-maps'