update instructure/rvm rubies
update instructure/rvm rubies

Change-Id: I459fa25b5c2ce433755a18fd3490ed0f2564671d
Reviewed-on: https://gerrit.instructure.com/170432
Tested-by: Bryan Petty <33564f6eff3d808d3eaaa056a1631fdcde5faed6@instructure.com>
Reviewed-by: Bryan Petty <33564f6eff3d808d3eaaa056a1631fdcde5faed6@instructure.com>
QA-Review: Bryan Petty <33564f6eff3d808d3eaaa056a1631fdcde5faed6@instructure.com>
Product-Review: Bryan Petty <33564f6eff3d808d3eaaa056a1631fdcde5faed6@instructure.com>

instructure/dockerfiles,instructure/dockerfiles,instructure/dockerfiles,instructure/dockerfiles