Make sure our current .gitlab-ci.yml is valid

This could prevent errors described in:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/8970

Everything we're using right now, should be valid of course.

spec/lib/ci/gitlab_ci_yaml_processor_spec.rb

@@ -4,6 +4,16 @@ module Ci
   describe GitlabCiYamlProcessor, lib: true do
     let(:path) { 'path' }
 
+    describe 'our current .gitlab-ci.yml' do
+      let(:config) { File.read("#{Rails.root}/.gitlab-ci.yml") }
+
+      it 'is valid' do
+        error_message = described_class.validation_message(config)
+
+        expect(error_message).to be_nil
+      end
+    end
+
     describe '#build_attributes' do
       describe 'coverage entry' do
         subject { described_class.new(config, path).build_attributes(:rspec) }