task: make helm_home, bin, and kubectl bin configurable

Refs /salt-formulas/salt-formula-helm#2
diff --git a/helm/kubectl_configured.sls b/helm/kubectl_configured.sls
index fbe2c48..26e3215 100644
--- a/helm/kubectl_configured.sls
+++ b/helm/kubectl_configured.sls
@@ -3,7 +3,7 @@
 include:
   - .kubectl_installed
 
-{{ constants.kubectl.config }}:
+{{ config.kubectl.config_file }}:
   file.managed:
     - source: salt://helm/files/kubeconfig.yaml.j2
     - mode: 400