First use case: Summarise Content

Class Prolog::UseCases::SummariseContent is the first of our use-case classes to be implemented. As per the "User-Eye View" in Issue #1, this produces (currently, a subset of) the data for a Web-site landing page or similar presentation.

This use case requires the Prolog::Core::Article class as defined in the prolog_core Gem version 0.4.0 or later. That version of the Gem does not implement CoRank-related attributes as described in this comment on Issue #2. Neither the logic nor packaging of the necessary CoRank support have yet been determined; once they are, an update to this Gem should add relevant entries to the Hash returned by SummariseContent#call.