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.