ENYO-1740: include authentication in the server tests

- ares.spec.js is now a mocha-based test suite (calling other mocha-
  based test suites)
- fsDropbox cookie is now labelled `dropbox_auth` (instead of
  `dropboxauth`), paving the road for other authentication cookies to be
  labelled `<service_id>_auth`.
- functionally equivalent query parameter (URL-encoded JSON-encoded
  `auth` Javascript object) is now `auth` (no longer `dropboxauth`) so
  that test suite can use a generic client-side parameter for several
  service providers

Enyo-DCO-1.1-Signed-off-by: Francois-Xavier KOWALSKI <francois-xavier.kowalski@hp.com>