For running single acceptance test, add an optional argument that will enable us to supply an argument if we want to just run one single test

Examples:
>  make test-acceptance tests.py:FullWorkflowOverrideTest.test_staff_override_at_end
Runs test_staff_override_at_end test of FullWorkflowOverrideTest class

>  make test-acceptance tests.py:FullWorkflowOverrideTest
Runs tests for FullWorkflowOverrideTest class

>  make test-acceptance tests.py
Runs all tests in tests.py

> make test-acceptance
This would work as it was previously i.e run all the acceptance tests