Bug 915156 - Part 3 - more cleanups

Move perf.js to tests/performance

Small cleanup variables and such post review.

Remove useless comment

Fix linter errors

fix details in test to be more test-ish
split out the integration to a separate app specific file

Move some non performance marionette stuff to a helper.

Move unlock screen to the helper.

Remove extraneous console.log

Fix linter issue

Get the RUNS env for number of runs

Make sure to reset mozPerfDurations for each test.

Fix perf event observer