rename "microbit" package to "core" #414 (#270)

* rename "microbit" package to "core" #414

* shouldn't edit the package id.

* updating package.json

* updated the wrong version

* missed updating pxt.json of tests

tests/base/pxt.json

@@ -6,8 +6,8 @@
     ],
     "public": true,
     "dependencies": {
-        "microbit": "*",
-        "microbit-radio": "*"
+        "core": "*",
+        "radio": "*"
     },
     "installedVersion": "file:."
 }