major rewrite of client

- refactored core logic into "requestApi", "operationApi",
  "getSwag" and "parseSwagOperations"
- removed Backbonejs dependency (Backbone events)
- removed User Interface module, and re-implemented as a plugin
- changed constructor to factory-callback pattern

- added "use strict"
- added debugging flag
- added more inline comments
implemented browser ui as plugin (WIP)