Introduce an option for testing binary API

Introduce an option for testing binary API

This patch introduces an option for choosing a configuration method in
tests. Supported methods are VAT and vpp's debug CLI.

 * Added new aprameter to run.sh to define method (--cfg-method [vat|cli]).
   Defaults to vat.
 * When running a test separately the method can be set as follows:
   $ sudo CFG_METHOD=cli ./tests/<test_case>.sh
   Again, it defaults to 'vat' if not provided.
 * Increased readability in test driver scripts when checking test
   status
 * When debugging you can stop test execution by running the test with WAIT=1:
    $ sudo WAIT=1 tests/<test_case>.sh

Change-Id: If851139cff072ba2e3b3594a3345763d360f3b59
Signed-off-by: Filip Tehlar <ftehlar@cisco.com>