Merge O4 into Py3

It's that time again!

I have a test in progress here: /fred/oz016/tdavies/projects/gstreamer_python_upgrade/testing/injection_tests/8000_test/16_02_tdavies__py3_merge_O4_dev

This should just be the ifo_set move. The gracedb upload fix is included, but made no changes.