Has questionnaire?!

This adds a predicate method => `#has_questionnaire` which returns the ruby boolean equivalent for the Job API field 'HasQuestionnaire'.

Also included are some meta-ish tests for the other predicate methods that act in the same way - they were untested before, the boy scout in me took over. Now if another boolean field needs to be added, you can add it to the mapping collection in the spec and the tests for the new field will write themselves as the spec runs (oOoOo magic :rainbow:).