Ignore InstanceVariableAssumption in controllers

Reek doesn't like using `before_action`s to set an instance variable.
Try as I might, I still haven't come up with a better pattern, however.
So, I'm just disabling this smell for this context entirely (at least
for now).

.reek.yml

@@ -27,6 +27,8 @@ directories:
   app/controllers:
     IrresponsibleModule:
       enabled: false
+    InstanceVariableAssumption:
+      enabled: false
   app/helpers:
     IrresponsibleModule:
       enabled: false