For non-XOS charts, use a global registry var, split docker image name/tag/pullPolicy

Change-Id: Icffc569e2c152e0b413f4c7b7d9a546bd9a3ef58
diff --git a/dhcp-server/Chart.yaml b/dhcp-server/Chart.yaml
index 844e777..6a1ea18 100644
--- a/dhcp-server/Chart.yaml
+++ b/dhcp-server/Chart.yaml
@@ -14,3 +14,4 @@
 
 name: dhcp-server
 version: 1.0.0
+appVersion: 'latest'