Removed the tests in GmfSetIterTestCase by explaining why they are redundant
event_based/core_test.py does not depend on random numbers any more
Relaxed the export test relying on a precise number of gmfs to be generated
Merge branch 'master' of github.com:gem/oq-engine into 1167310-fix-tests
Small change
Merge pull request #1131 from gem/1167310-fix-tests

Fix the tests of the event_based depending on random number details