Support Nginx custom configuration in Ingress

This PS support to render nginx configuration to be controlled. It
enables to config nginx paramter in values.yaml

Change-Id: Ie36efddceeb2feb1aedb88f5852fb706c161aa05
Closes-Bug: 1712263

ingress/templates/nginx-custom-configuration.yaml

@@ -1,7 +1,25 @@
+{{/*
+Copyright 2017 The Openstack-Helm Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/}}
+
+{{- $envAll := . }}
+---
 apiVersion: v1
 kind: ConfigMap
 metadata:
   name: nginx-custom-configuration
 data:
-  enable-underscores-in-headers: "true"
+{{ toYaml .Values.config | indent 2 }}
 

ingress/values.yaml

@@ -81,3 +81,6 @@ endpoints:
       https: 443
 
 deployment_type: Deployment
+
+config:
+  enable-underscores-in-headers: "true"