checks if babel is installed globally and displays correct cli messag…

…e - fixes babel#5228

packages/babel/cli.js

@@ -1,10 +1,13 @@
 #!/usr/bin/env node
+import isGlobal from "is-global"
+
+const globalMessage = isGlobal() ? ' -g' : '';
 
 console.error("You have mistakenly installed the `babel` package, which is a no-op in Babel 6.\n" +
   "Babel's CLI commands have been moved from the `babel` package to the `babel-cli` package.\n" +
   "\n" +
-  "    npm uninstall babel\n" +
-  "    npm install babel-cli\n" +
+  "    npm uninstall" + globalMessage + " babel\n" +
+  "    npm install" + globalMessage + " babel-cli\n" +
   "\n" +
   "See http://babeljs.io/docs/usage/cli/ for setup instructions.");
 process.exit(1);

packages/babel/package.json

@@ -10,5 +10,8 @@
     "babel": "./cli.js",
     "babel-node": "./cli.js",
     "babel-external-helpers": "./cli.js"
+  },
+  "dependencies": {
+    "is-global": "^0.1.0"
   }
 }