Merge branch 'master' into milestone-ref

CHANGELOG

app/controllers/admin/application_settings_controller.rb

app/controllers/application_controller.rb

app/controllers/profiles/two_factor_auths_controller.rb

app/helpers/auth_helper.rb

app/models/application_setting.rb

app/views/admin/application_settings/_form.html.haml

app/views/profiles/keys/new.html.haml

app/views/profiles/two_factor_auths/new.html.haml

config/routes.rb

db/migrate/20151218154042_add_tfa_to_application_settings.rb

db/migrate/20151221234414_add_tfa_additional_fields.rb

db/schema.rb

doc/README.md

doc/api/users.md

doc/ci/README.md

doc/ci/triggers/README.md

doc/ci/triggers/img/builds_page.png

doc/ci/triggers/img/trigger_single_build.png

doc/ci/triggers/img/trigger_variables.png