Parametуrize glance image size

We should have ability to modify this value, because sometimes 30Gb is
not enough for prepared images.

Change-Id: I594c34c416c5aba8a1892756014d0503bff80b62
Related-Prod: PROD-21911
diff --git a/nginx/server/proxy/openstack/glance.yml b/nginx/server/proxy/openstack/glance.yml
index 3479296..9cdd702 100644
--- a/nginx/server/proxy/openstack/glance.yml
+++ b/nginx/server/proxy/openstack/glance.yml
@@ -3,6 +3,7 @@
     nginx_proxy_openstack_api_host: ${_param:cluster_public_host}
     nginx_proxy_openstack_glance_protocol: 'http'
     nginx_proxy_openstack_glance_host: ${_param:glance_service_host}
+    nginx_proxy_openstack_glance_image_size: '30000m'
     nginx_proxy_openstack_api_address: 0.0.0.0
   nginx:
     server:
@@ -18,7 +19,7 @@
             host: ${_param:nginx_proxy_openstack_glance_host}
             port: 9292
             protocol: ${_param:nginx_proxy_openstack_glance_protocol}
-            size: 30000m
+            size:  ${_param:nginx_proxy_openstack_glance_image_size}
           host:
             name: ${_param:nginx_proxy_openstack_api_host}
             port: 9292