Handle the hardcoded configuration values

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

    glance:
      server:
        configmap:
          glace_api:
            DEFAULT:
              image_member_quota = 128
              image_property_quota = 128
              image_tag_quota = 128
              image_location_quota = 10
              user_storage_quota = 0
          glace_registry:
            DEFAULT:
              image_member_quota = 128
              image_property_quota = 128
              image_tag_quota = 128
              image_location_quota = 10
              user_storage_quota = 0
          ...

Change-Id: Ie74a66321ec39d154cac95d3315381c395b5582c
Related-Prod: PROD-29040
diff --git a/README.rst b/README.rst
index 0c90281..8fde47d 100644
--- a/README.rst
+++ b/README.rst
@@ -354,7 +354,7 @@
           cache_cleaner:
             hour: '5'
             minute: '30'
-            daymonth: '*/2'
+            daymonth: '\*/2'
 
 
 Image cache settings
@@ -477,6 +477,29 @@
         ...
         show_multiple_locations: True
 
+Change default resource quotas using configmap template settings
+========
+
+.. code-block:: yaml
+
+    glance:
+      server:
+        configmap:
+          glace_api:
+            DEFAULT:
+              image_member_quota = 128
+              image_property_quota = 128
+              image_tag_quota = 128
+              image_location_quota = 10
+              user_storage_quota = 0
+          glace_registry:
+            DEFAULT:
+              image_member_quota = 128
+              image_property_quota = 128
+              image_tag_quota = 128
+              image_location_quota = 10
+              user_storage_quota = 0
+
 Usage
 =====