Simplify instance var assignments in Question::Base
Simplify instance var assignments in Question::Base

There's nowhere else these instance variables could've been assigned prior to
the class' constructor, so it doesn't seem necessary to include the `||` check
to see whether they are already assigned.

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