EE: Resolve "A lot of constants redefinition warnings"
EE for https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19286
Additionally, eliminate CE/EE difference for config/initializers/omniauth.rb
EE for https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19286
Additionally, eliminate CE/EE difference for config/initializers/omniauth.rb