groundwork for asset caching

package-lock.json

@@ -5494,6 +5494,15 @@
         "is-buffer": "1.1.5"
       }
     },
+    "klaw": {
+      "version": "1.3.1",
+      "resolved": "https://registry.npmjs.org/klaw/-/klaw-1.3.1.tgz",
+      "integrity": "sha1-QIhDO0azsbolnXh4XY6W9zugJDk=",
+      "dev": true,
+      "requires": {
+        "graceful-fs": "4.1.11"
+      }
+    },
     "known-css-properties": {
       "version": "0.2.0",
       "resolved": "https://registry.npmjs.org/known-css-properties/-/known-css-properties-0.2.0.tgz",
@@ -10698,6 +10707,40 @@
         "time-stamp": "2.0.0"
       }
     },
+    "webpack-manifest-plugin": {
+      "version": "1.3.1",
+      "resolved": "https://registry.npmjs.org/webpack-manifest-plugin/-/webpack-manifest-plugin-1.3.1.tgz",
+      "integrity": "sha512-OW7in/4VksQVnQcDJClv7YnOs/ruOqzPriT46z+qe6i1qINfZkmCNoxNG3r5J19VBSmO0KF1vn3Ute0yTKaeHQ==",
+      "dev": true,
+      "requires": {
+        "fs-extra": "0.30.0",
+        "lodash": "4.17.4"
+      },
+      "dependencies": {
+        "fs-extra": {
+          "version": "0.30.0",
+          "resolved": "https://registry.npmjs.org/fs-extra/-/fs-extra-0.30.0.tgz",
+          "integrity": "sha1-8jP/zAjU2n1DLapEl3aYnbHfk/A=",
+          "dev": true,
+          "requires": {
+            "graceful-fs": "4.1.11",
+            "jsonfile": "2.4.0",
+            "klaw": "1.3.1",
+            "path-is-absolute": "1.0.1",
+            "rimraf": "2.6.1"
+          }
+        },
+        "jsonfile": {
+          "version": "2.4.0",
+          "resolved": "https://registry.npmjs.org/jsonfile/-/jsonfile-2.4.0.tgz",
+          "integrity": "sha1-NzaitCi4e72gzIO1P6PWM6NcKug=",
+          "dev": true,
+          "requires": {
+            "graceful-fs": "4.1.11"
+          }
+        }
+      }
+    },
     "webpack-sources": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/webpack-sources/-/webpack-sources-1.0.1.tgz",