use node-copy-webpack-plugin from system

debian/control

@@ -304,6 +304,7 @@ Depends: ${shlibs:Depends}, ${misc:Depends}, ruby | ruby-interpreter,
  node-babel-preset-latest,
  node-babel-preset-stage-2,
  node-bootstrap-sass,
+ node-copy-webpack-plugin,
  node-core-js,
  node-d3,
  node-eslint-plugin-html,

debian/patches/0420-use-system-libs.patch

@@ -1,6 +1,6 @@
 --- a/package.json
 +++ b/package.json
-@@ -12,60 +12,29 @@
+@@ -12,60 +12,28 @@
      "webpack-prod": "NODE_ENV=production webpack --config config/webpack.config.js"
    },
    "dependencies": {
@@ -13,7 +13,7 @@
 -    "babel-preset-stage-2": "^6.22.0",
 -    "bootstrap-sass": "^3.3.6",
      "compression-webpack-plugin": "^0.3.2",
-     "copy-webpack-plugin": "^4.0.1",
+-    "copy-webpack-plugin": "^4.0.1",
 -    "core-js": "^2.4.1",
      "cropper": "^2.3.0",
      "css-loader": "^0.28.0",

debian/patches/0430-remove-devdeps.patch

@@ -1,6 +1,6 @@
 --- a/package.json
 +++ b/package.json
-@@ -37,25 +37,5 @@
+@@ -36,25 +36,5 @@
      "webpack-bundle-analyzer": "^2.8.2"
    },
    "devDependencies": {