- Introduce various decorators for annotating tests that depend on
  specific services.
- Add dedicated make target for running acceptance tests locally.
- Create wrapper script that can run the entire acceptance test suite or
  a specific set of tasks.
- Document process for running acceptance tests in README.

Companion PR: https://github.com/edx/configuration/pull/2790
(automates setup steps that have to be performed once to prepare
Analytics Devstack for running acceptance tests)