nunaliit2-js: Add caching to dbPerspective

Issue #272
nunaliit2-js: Add "use strict" to some files

Issue #276
nunaliit2-js-external: Add libraries for jquery.qtip.js

nunaliit2-couch-sdk: Add the QTip library to the main index.html

Issue #280
nunaliit2-js: Improvements to dbPerspective

Issue #272