Split up tests for DrupalUserRegistry into API and non-API related tests.
Ignore _beforeSuite() and _afterSuite() hooks from code coverage: the calls to manageTestUsers() these methods make will (eventually) be tested elsewhere, more directly.
Add command to generate coverage reports and copy them to the docs/ directory.
Test that calling DrupalUserRegistry::manageUsers() with empty or invalid operation parameter throws the expected exception.