Load XOS certificates from files rather than embedding in the values file

Change-Id: Iebcba439adfdb8e9358067a0e84ab790b39a17d4
diff --git a/xos-core/templates/coreapi-cert-secret.yaml b/xos-core/templates/coreapi-cert-secret.yaml
index 048f552..b70cba6 100644
--- a/xos-core/templates/coreapi-cert-secret.yaml
+++ b/xos-core/templates/coreapi-cert-secret.yaml
@@ -20,5 +20,5 @@
   namespace: default
 type: kubernetes.io/tls
 data:
-  tls.crt: {{ .Values.secrets.core_api_cert }}
-  tls.key: {{ .Values.secrets.core_api_key }}
+  tls.crt: {{ .Files.Get "pki/xos-core.pem" | b64enc }}
+  tls.key: {{ .Files.Get "pki/xos-core.key" | b64enc }}