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

restapi/admin_tenants_test.go

@@ -21,6 +21,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"io"
 	"io/ioutil"
 	"net/http"
 	"reflect"
@@ -47,6 +48,8 @@ var opClientTenantGetMock func(ctx context.Context, namespace string, tenantName
 var opClientTenantPatchMock func(ctx context.Context, namespace string, tenantName string, pt types.PatchType, data []byte, options metav1.PatchOptions) (*v1.Tenant, error)
 var opClientTenantListMock func(ctx context.Context, namespace string, opts metav1.ListOptions) (*v1.TenantList, error)
 var httpClientGetMock func(url string) (resp *http.Response, err error)
+var httpClientPostMock func(url, contentType string, body io.Reader) (resp *http.Response, err error)
+var httpClientDoMock func(req *http.Request) (*http.Response, error)
 var k8sclientGetSecretMock func(ctx context.Context, namespace, secretName string, opts metav1.GetOptions) (*corev1.Secret, error)
 var k8sclientGetServiceMock func(ctx context.Context, namespace, serviceName string, opts metav1.GetOptions) (*corev1.Service, error)
 
@@ -75,6 +78,16 @@ func (h httpClientMock) Get(url string) (resp *http.Response, err error) {
 	return httpClientGetMock(url)
 }
 
+// mock function of post()
+func (h httpClientMock) Post(url, contentType string, body io.Reader) (resp *http.Response, err error) {
+	return httpClientPostMock(url, contentType, body)
+}
+
+// mock function of Do()
+func (h httpClientMock) Do(req *http.Request) (*http.Response, error) {
+	return httpClientDoMock(req)
+}
+
 func (c k8sClientMock) getSecret(ctx context.Context, namespace, secretName string, opts metav1.GetOptions) (*corev1.Secret, error) {
 	return k8sclientGetSecretMock(ctx, namespace, secretName, opts)
 }