allow rails 5.2
allow rails 5.2

Change-Id: I46f63ace2be641e938c17901260fb4376fec2cdf
Reviewed-on: https://gerrit.instructure.com/146474
Tested-by: Jenkins
Reviewed-by: Rob Orton <7e09c9d3e96378bf549fc283fd6e1e5b7014cc33@instructure.com>
Product-Review: James Williams  <3a5f4ed991dbfa5c9ef76ad729d240ca12f62180@instructure.com>
QA-Review: James Williams  <3a5f4ed991dbfa5c9ef76ad729d240ca12f62180@instructure.com>

instructure/analytics,instructure/analytics,instructure/analytics