Require grainstore 0.9.1 for automatic styles reset on mapnik upgrade

npm-shrinkwrap.json

@@ -180,7 +180,7 @@
       "version": "1.3.3"
     },
     "grainstore": {
-      "version": "0.9.0",
+      "version": "0.9.1",
       "dependencies": {
         "carto": {
           "version": "0.9.2",

package.json

@@ -21,7 +21,7 @@
         "cluster2": "git://github.com/CartoDB/cluster2.git#28cde11",
         "node-varnish": "0.1.1",
         "underscore"  : "~1.3.3",
-        "grainstore"  : "~0.9.0",
+        "grainstore"  : "~0.9.1",
         "windshaft"  : "~0.6.1",
         "step": "0.0.x",
         "generic-pool": "1.0.x",