CB-8125 Reorganised and cleaned up test suite.

Audited all calls to done() to ensure correct async execution. Removed some redundant code. Removed depencency on mobile-spec: tests now run even if started independently. Tested without plugin-test-framework and with it, on Windows, iOS, and Android.

Corresponding JIRA link: https://issues.apache.org/jira/browse/CB-8125.