Add default GA collectors for visit-visas dashbaord

add: browser-usage - backfilled 2014-09-01 - 2014-12-07
add: device-usage - backfilled 2014-09-01 - 2014-12-07
add: new-returning-users - backfilled - 2014-09-01 - 2014-12-07
add: realtime - no backfill

updated: cronjobs