Remove Question::Base#method_missing
Remove Question::Base#method_missing

This is no longer necessary because `@predicates` is never set to anything
other than an empty hash.

aledelcueto/smart-answers,stwalsh/smart-answers,stwalsh/smart-answers,aledelcueto/smart-answers,alphagov/smart-answers,aledelcueto/smart-answers,stwalsh/smart-answers,alphagov/smart-answers,aledelcueto/smart-answers,alphagov/smart-answers,stwalsh/smart-answers,alphagov/smart-answers