Added call to donate after npm install (optional)

Author: monkeywithacupcake

package.json

@@ -23,7 +23,8 @@
     "browser": "browserify ./index.js -p licensify -o browser.js -s brain",
     "browser-min": "browserify ./index.js -p licensify -s brain -g uglifyify -o browser.min.js",
     "make": "rimraf dist && npm run dist && git add ./dist && npm run browser && npm run browser-min",
-    "clean": "rimraf node_modules"
+    "clean": "rimraf node_modules",
+    "postinstall": "opencollective postinstall"
   },
   "main": "./index.js",
   "devDependencies": {
@@ -75,7 +76,12 @@
   "license": "MIT",
   "dependencies": {
     "gpu.js": "^1.2.0",
+    "opencollective": "^1.0.3",
     "thaw.js": "^2.0.0"
   },
-  "typings": "./index.d.ts"
-}
+  "typings": "./index.d.ts",
+  "collective": {
+    "type": "opencollective",
+    "url": "https://opencollective.com/brainjs"
+  }
+}