Add cross-env into the mix

this way `npm run build` will work on Windows too :D

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

package.json

@@ -30,7 +30,7 @@
     "build:res": "node scripts/copy-res.js",
     "build:modernizr": "modernizr -c .modernizr.json -d src/vector/modernizr.js",
     "build:compile": "babel --source-maps -d lib src",
-    "build:bundle": "NODE_ENV=production webpack -p --progress",
+    "build:bundle": "cross-env NODE_ENV=production webpack -p --progress",
     "build:bundle:dev": "webpack --optimize-occurence-order --progress",
     "build:electron": "npm run clean && npm run build && build -wml --ia32 --x64",
     "build": "node scripts/babelcheck.js && npm run build:res && npm run build:bundle",
@@ -38,7 +38,7 @@
     "dist": "scripts/package.sh",
     "start:res": "node scripts/copy-res.js -w",
     "start:js": "webpack-dev-server --output-filename=bundles/_dev_/[name].js --output-chunk-file=bundles/_dev_/[name].js -w --progress",
-    "start:js:prod": "NODE_ENV=production webpack-dev-server -w --progress",
+    "start:js:prod": "cross-env NODE_ENV=production webpack-dev-server -w --progress",
     "start": "node scripts/babelcheck.js && parallelshell \"npm run start:res\" \"npm run start:js\"",
     "start:prod": "parallelshell \"npm run start:res\" \"npm run start:js:prod\"",
     "lint": "eslint src/",
@@ -93,6 +93,7 @@
     "babel-preset-stage-2": "^6.17.0",
     "chokidar": "^1.6.1",
     "cpx": "^1.3.2",
+    "cross-env": "^4.0.0",
     "css-raw-loader": "^0.1.1",
     "electron-builder": "^11.2.4",
     "electron-builder-squirrel-windows": "^11.2.1",