Use Helm's built-in support for namespaces

Remove our non-standard namespace variable and use .Release.Namespace
to put fission deployments and services into.

(We still need the functionNamespace parameter, to customize what
namespace fission puts functions into.)

charts/fission/templates/svc.yaml

@@ -2,7 +2,7 @@ apiVersion: v1
 kind: Service
 metadata:
   name: router
-  namespace: {{ .Values.namespace }}
+  namespace: {{ .Release.Namespace }}
   labels:
     svc: router
     chart: "{{ .Chart.Name }}-{{ .Chart.Version }}"
@@ -20,7 +20,7 @@ apiVersion: v1
 kind: Service
 metadata:
   name: controller
-  namespace: {{ .Values.namespace }}
+  namespace: {{ .Release.Namespace }}
   labels:
     svc: controller
     chart: "{{ .Chart.Name }}-{{ .Chart.Version }}"