Fixed an ordering bug in pg_importer_test.py
Fixed a bug due to the version of mock used
Fixed also a bug in the PerformanceMonitor
Merge pull request #1133 from gem/fix-mock-issue

Fixed a bug in event_based/core_test.py due to the version of mock used
Merge branch 'master' of https://github.com/gem/oq-engine into multi-hazard-curves