enable colors for rails 3 rspec

Change-Id: I92afbb4182ee3133e0d634ad816a23b4729f5f2c
Reviewed-on: https://gerrit.instructure.com/37228
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Brian Palmer <brianp@instructure.com>
QA-Review: Jeremy Putnam <jeremyp@instructure.com>
Product-Review: Nick Cloward <ncloward@instructure.com>