Use method that creates runners registration token

`runners_registration_token` now creates a new token if it is blank.

app/models/application_setting.rb

@@ -134,4 +134,8 @@ class ApplicationSetting < ActiveRecord::Base
       /x)
     self.restricted_signup_domains.reject! { |d| d.empty? }
   end
+
+  def runners_registration_token
+    ensure_runners_registration_token!
+  end
 end

app/models/concerns/token_authenticatable.rb

@@ -46,5 +46,4 @@ module TokenAuthenticatable
       break token unless self.class.unscoped.find_by(token_field => token)
     end
   end
-
 end

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

@@ -3,7 +3,7 @@
     To register a new runner you should enter the following registration token.
     With this token the runner will request a unique runner token and use that for future communication.
     Registration token is
-    %code{ id: 'runners-token' } #{current_application_settings.ensure_runners_registration_token}
+    %code{ id: 'runners-token' } #{current_application_settings.runners_registration_token}
 
 .bs-callout.clearfix
   .pull-left

lib/ci/api/helpers.rb

@@ -19,7 +19,7 @@ module Ci
       end
 
       def runner_registration_token_valid?
-        params[:token] == current_application_settings.ensure_runners_registration_token
+        params[:token] == current_application_settings.runners_registration_token
       end
 
       def update_runner_last_contact

spec/features/admin/admin_runners_spec.rb

@@ -63,7 +63,7 @@ describe "Admin Runners" do
   end
 
   describe 'runners registration token' do
-    let!(:token) { current_application_settings.ensure_runners_registration_token }
+    let!(:token) { current_application_settings.runners_registration_token }
     before { visit admin_runners_path }
 
     it 'has a registration token' do

spec/requests/ci/api/runners_spec.rb

@@ -8,7 +8,6 @@ describe Ci::API::API do
 
   before do
     stub_gitlab_calls
-    stub_application_setting(ensure_runners_registration_token: registration_token)
     stub_application_setting(runners_registration_token: registration_token)
   end