spec: don't break feature definitions in feature_spec

fixes a problem where running feature_spec will break
any future specs in the same run that depend on features

Change-Id: Ia81c8f0ff89a475b84290bff0ed996ddcd3aaeea
Reviewed-on: https://gerrit.instructure.com/43731
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Jeremy Stanley <jeremy@instructure.com>
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
QA-Review: James Williams  <jamesw@instructure.com>