Change handling of warranty of nodes

• rake gen:dell-product-data to retrieve via Dell API
• manual add of the warranty for non-dell clusters
• rake gen:puppet:cluster to generate the hieradata/clusters.yaml
• minor fixes about clusters (typo) and servers description (homogeneity of YAML files name)

data/grid5000/sites/grenoble/clusters/dahu/nodes/dahu-1.json

@@ -13,9 +13,11 @@
   },
   "bmc_version": "5.10.50.00",
   "chassis": {
+    "manufactured_at": "2017-12-13",
     "manufacturer": "Dell Inc.",
     "name": "PowerEdge C6420",
-    "serial": "17TRSM2"
+    "serial": "17TRSM2",
+    "warranty_end": "2024-12-13"
   },
   "exotic": false,
   "kavlan": {