[spec/feature] use correct table id
Merge pull request #317 from Genshin/fix_course_create_spec

[spec/feature] use correct table id
Various enhancements for Gaku::User:

* Remove defunct Gaku::User#has_role?
* Refactor and fix logic for Gaku::User#role?
* Add specs for all scopes and methods #to_s, #role?
* Document Gaku::User#find_first_by_auth_conditions
Merge branch 'master' of github.com:Genshin/gaku into add-tests-for-users