Move nut-score into website/sandbox

Also move some .gitignore entries from the top-level .gitignore into a
subdirectory .gitignore.

nut-score/bsconfig.json

@@ -1,21 +0,0 @@
-{
-  "name": "reason-react-examples",
-  "reason": {
-    "react-jsx": 3
-  },
-  "sources": {
-    "dir" : "src",
-    "subdirs" : true
-  },
-  "bsc-flags": ["-bs-super-errors", "-bs-no-version-header"],
-  "package-specs": [{
-    "module": "commonjs",
-    "in-source": true
-  }],
-  "suffix": ".bs.js",
-  "namespace": true,
-  "bs-dependencies": [
-    "reason-react"
-  ],
-  "refmt": 3
-}