Remove Entrypoint from Kompose object

We had Command and Args together with Entrypoint in Kompose object.
This doesn't make much sense, as Entrypoint and Command are same thing.
I've removed Entrypoint from Kompose object in favor of Command to keep
same naming convensions as in Kubernetes.

Entrypoint from docker-compose.yml is now saved to Command and Command
is saved to Args (http://kubernetes.io/docs/user-guide/containers/).

docker-compose.yml | Kompose object
-------------------|---------------
  Entrypoint       |    Command
   Command         |     Args

pkg/loader/compose/compose.go

@@ -151,8 +151,8 @@ func (c *Compose) LoadFile(file string) kobject.KomposeObject {
 			serviceConfig := kobject.ServiceConfig{}
 			serviceConfig.Image = composeServiceConfig.Image
 			serviceConfig.ContainerName = composeServiceConfig.ContainerName
-			serviceConfig.Entrypoint = composeServiceConfig.Entrypoint
-			serviceConfig.Command = composeServiceConfig.Command
+			serviceConfig.Command = composeServiceConfig.Entrypoint
+			serviceConfig.Args = composeServiceConfig.Command
 
 			// load environment variables
 			envs := loadEnvVars(composeServiceConfig.Environment.ToMap())