Merge branch 'backport-ee-2456' into 'master'

app/controllers/admin/applications_controller.rb

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

app/views/admin/applications/index.html.haml

app/views/admin/applications/show.html.haml

...sed/skip-oauth-authorization-for-trusted-applications.yml

config/initializers/doorkeeper.rb

...0170717200542_add_trusted_column_to_oauth_applications.rb

db/schema.rb

doc/integration/oauth_provider.md

spec/controllers/admin/applications_controller_spec.rb

spec/controllers/oauth/authorizations_controller_spec.rb

spec/features/admin/admin_manage_applications_spec.rb