make hiera deep merge (requires deep_merge gem)
diff --git a/puppet/hiera.yaml b/puppet/hiera.yaml
index c6ec997..3f1cca4 100644
--- a/puppet/hiera.yaml
+++ b/puppet/hiera.yaml
@@ -13,3 +13,4 @@
 :yaml:
   :datadir: '/tmp/kitchen/hiera'
 
+:merge_behavior: deeper