update package dependencies

package.json

@@ -62,15 +62,15 @@
   },
   "dependencies": {
     "debug": "^2.2.0",
-    "js-base64": "^2.1.9",
+    "js-base64": "^2.3.2",
     "js-yaml": "^3.5.2",
-    "json-refs": "^2.1.5",
+    "json-refs": "^3.0.2",
     "json-schema-faker": "^0.3.2",
     "lodash": "^4.2.0",
     "native-promise-only": "^0.8.1",
     "path-to-regexp": "^1.2.1",
     "swagger-methods": "^1.0.0",
     "swagger-schema-official": "2.0.0-bab6bed",
-    "z-schema": "^3.18.0"
+    "z-schema": "^3.18.4"
   }
 }