qa_tests/hazard/event_based/case_8:

Removed case 8; I couldn't get it to converge with the expected results in a
reasonable run time.
qa_tests/hazard/event_based:

Updated the GSIM references in cases 2 and 4.
qa_tests/hazard/event_based:

Corrected source model names in cases 2 and 4; they were copied from the
classical cases.
qa_tests/hazard/event_based:

Added `hazard` nose attr to cases 2 and 4.