Revert "XOS/NEM charts, use a global registry var, split docker image name/tag/pullPolicy"

This reverts commit 1f58c2afbd680c8c618bff6f66e9982515dd1caf.

Change-Id: I0d7ef37a420168276472675b005482d6d11daabd
diff --git a/xos-db/values.yaml b/xos-db/values.yaml
index 8428769..8bb026d 100644
--- a/xos-db/values.yaml
+++ b/xos-db/values.yaml
@@ -15,13 +15,8 @@
 
 # XOS Postgres database related values
 
-image:
-  repository: 'postgres'
-  tag: '{{ .Chart.AppVersion }}'
-  pullPolicy: 'Always'
-
-global:
-  registry: ""
+imagePullPolicy: 'Always'
+postgresImage: 'postgres:10.3-alpine'
 
 # Database name/username/password
 xosDBName: 'xos'