Enhanced qatest_1, so that it subsumes regression_1 and regression_2

This pull request implements https://bugs.launchpad.net/oq-engine/+bug/1225288 and more. Now qatest_1 is testing all the outputs of the event based risk calculator, so that the tests  regression_1 and regression_2 are not needed anymore. I have also added a fast test qatest_2, which tests the disaggregation outputs, and is useful also as a unit test. See https://ci2.openquake.org/job/zdevel_oq-engine/419