move plan analysis to client side

Clients are responsible to determine if plans are executable.
Plan rating makes more sense on the client side where plans are
presented to the user.
Change plan JSON Schema to include information about distance between
provisioned concepts (published properties and realized
functionalities) and drop plan rating.
remove plan rating and collectors from planner
move Repository back to module planner

Change from int to double for measuring distance between request and
offer.
refactor service module structure
use lazy value properties

Make use of lazy value properties (introduced with
864b447a2d26254f5a56fb2ce1b6c5908fb40c5c) where applicable.
tweak composer widget UI

Add note about goal mashup description language being automatically
determined.
Show number of widgets, steps, and interactions for each plan in
selection view.