Merge branch 'consistent-deployment_platform' into 'master'

Unify deployment_platform interface with EE

See merge request gitlab-org/gitlab-ce!17594

app/models/concerns/deployment_platform.rb

 module DeploymentPlatform
-  def deployment_platform
+  # EE would override this and utilize the extra argument
+  def deployment_platform(environment: nil)
     @deployment_platform ||=
       find_cluster_platform_kubernetes ||
       find_kubernetes_service_integration ||

app/models/environment.rb

@@ -225,7 +225,7 @@ class Environment < ActiveRecord::Base
   end
 
   def deployment_platform
-    project.deployment_platform
+    project.deployment_platform(environment: self)
   end
 
   private