Add the framework for a test suite

Add the framework for a test suite

Add the framework for a test suite for the Telepathy backend, including
a dummy account manager, account and connection, to allow complete control
over the personas created in libfolks.

This comes with a test case framework which wraps the GLib test framework,
used by a test case which tests that all expected individuals are exposed by
the individual aggregator.

Heavily based on work by Travis Reitter <travis.reitter@collabora.co.uk>.