remove __ from event keys wherever possible

the sample composite events and others have __ instead of _ for the amqp events. for example
{"wf_user": "rynge",
"root__xwf__id": "d8939648-74cd-4809-a6ee-f640b69ba155",
"job__id": "create_dir_synthetic_0_staging_site",
"submit__dir": "/lfs1/scratch/rynge/workflows/rynge/pegasus/synthetic/20180829T094516-0700",
"site": "local",
"pegasus__version": "4.9.0dev",
"event": "stampede.job_inst.composite",
"xwf__id": "d8939648-74cd-4809-a6ee-f640b69ba155",
"work_dir": "/lfs1/scratch/rynge/workflows/rynge/pegasus/synthetic/20180829T094516-0700",
"wf__ts": 1535561116,
"ts": 1535561214,
"local__dur": 4,
"sched__id": "4147075.0",
"multiplier_factor": "1",
"submit__hostname": "bamboo.isi.edu",
"stderr__file": "00/01/create_dir_synthetic_0_staging_site.err.000",
"int_error_count": 0,
"status": 0,
"dag": "synthetic-0.dag",
"js__id": 4,
"job_inst__id": 1,
"user": "rynge",
"stdout__text": "#@ 1 stdout%0A2018-08-29 09:46:50,736 INFO: Reading URL pairs from stdin%0A2018-08-29 09:46:50,737 INFO: 1 transfers loaded%0A2018-08-29 09:46:50,737 INFO: PATH=/usr/bin:/bin%0A2018-08-29 09:46:50,737 INFO: LD_LIBRARY_PATH=%0A2018-08-29 09:46:50,764 INFO: --------------------------------------------------------------------------------%0A2018-08-29 09:46:50,765 INFO: Starting transfers - attempt 1%0A2018-08-29 09:46:52,831 INFO: Tool found: gfal-mkdir Version: 2.15.4 Path: /usr/bin/gfal-mkdir%0A2018-08-29 09:46:52,831 INFO: gfal-mkdir -p %27gsiftp://bamboo.isi.edu/nfs/ccg4/scratch-purge-no-backups/rynge/intermediate/rynge/pegasus/synthetic/20180829T094516-0700%27%0A2018-08-29 09:46:54,348 INFO: --------------------------------------------------------------------------------%0A2018-08-29 09:46:54,348 INFO: Stats: no local files in the transfer set%0A2018-08-29 09:46:54,348 INFO: All transfers completed successfully.%0A", "dax": "/nfs/asd2/rynge/pegasus/synthetic-integrity-test/dax.xml",
"stdout__file": "00/01/create_dir_synthetic_0_staging_site.out.000",
"stderr__text": "",
"jobtype": "6",
"exitcode": "0"}