Handle the hardcoded configuration values

This patch allows to customize the hardcoded configuration values,
as well as introduce new configuration options for cinder services
by configmap template with the specified section:

  cinder:
    controller:
      configmap:
        DEFAULT:
          quota_volumes: 15
          quota_snapshots: 15
          quota_consistencygroups: 15
          quota_groups: 15
          quota_gigabytes: 1500
          quota_backups: 15
          quota_backup_gigabytes: 1500
          reservation_expire: 86400
          reservation_clean_interval: 86400
          until_refresh: 0
          max_age: 0
          quota_driver: cinder.quota.DbQuotaDriver
          use_default_quota_class: true
          per_volume_size_limit: 100

Change-Id: Ia8d5e33ea9532c8b670bc7ba5ffd36bb527cd104
Related-Prod: PROD-29040
diff --git a/README.rst b/README.rst
index 35a5188..5b55e69 100644
--- a/README.rst
+++ b/README.rst
@@ -933,6 +933,30 @@
          username: cinder
          password: pswd
 
+Change default resource quotas using configmap template settings
+========
+
+.. code-block:: yaml
+
+    cinder:
+      controller:
+        configmap:
+          DEFAULT:
+            quota_volumes: 15
+            quota_snapshots: 15
+            quota_consistencygroups: 15
+            quota_groups: 15
+            quota_gigabytes: 1500
+            quota_backups: 15
+            quota_backup_gigabytes: 1500
+            reservation_expire: 86400
+            reservation_clean_interval: 86400
+            until_refresh: 0
+            max_age: 0
+            quota_driver: cinder.quota.DbQuotaDriver
+            use_default_quota_class: true
+            per_volume_size_limit: 100
+
 Upgrades
 ========