Product license verification in Console (#518)

Operator UI - Provide and store License key
- New License section in Operator UI will allow user to provide the
  license key via input form
- New License section in Operator UI will allow the user to fetch the
  license key using subnet credentials
-  Console backend has to verify provided license is valid -
   https://godoc.org/github.com/minio/minio/pkg/licverifier#example-package
-  Console backend has to store the license key in k8s secrets

Operator UI - Set license to tenant during provisioning
- Check if license key exists in k8s secret during tenant creation
- If License is present attach the license-key jwt to the new console
tenant via an environment variable

Operator UI - Set license for an existing tenant
- Tenant view will display information about the current status of the
  Tenant License
- If Tenant doesn't have a License then Operator-UI will allow to attach
new license by clicking the Add License button
- Console backend will extract the license from the k8s secret and save
the license-key jwt in the tenant console environment variable and
redeploy

cluster/const.go

@@ -1,5 +1,5 @@
 // This file is part of MinIO Kubernetes Cloud
-// Copyright (c) 2019 MinIO, Inc.
+// Copyright (c) 2020 MinIO, Inc.
 //
 // This program is free software: you can redistribute it and/or modify
 // it under the terms of the GNU Affero General Public License as published by
@@ -21,5 +21,4 @@ const (
 	ConsoleK8SAPIServerTLSRootCA = "CONSOLE_K8S_API_SERVER_TLS_ROOT_CA"
 	ConsoleMinioImage            = "CONSOLE_MINIO_IMAGE"
 	ConsoleMCImage               = "CONSOLE_MC_IMAGE"
-	ConsoleNamespace             = "CONSOLE_NAMESPACE"
 )