Break CLI process when Node is not supported

As old versions of Node.js cannot be used anymore (after transpiling to ES6), we should break the process when such case happens.
Use only var instead of let, const, as only var keyword is supported in Node.js 0.10.x

Author: rosen-vladimirov

bin/nativescript.js

@@ -1,4 +1,8 @@
 #!/usr/bin/env node
 
 "use strict";
+var path = require("path");
+var node = require("../package.json").engines.node;
+require(path.join(__dirname, "..", "lib", "common", "verify-node-version")).verifyNodeVersion(node, "NativeScript");
+
 require("../lib/nativescript-cli.js");

lib/common

@@ -1,7 +1,3 @@
-let node = require("../package.json").engines.node;
-// this call must be first to avoid requiring c++ dependencies
-require("./common/verify-node-version").verifyNodeVersion(node, "NativeScript", "2.5.0");
-
 require("./bootstrap");
 import * as fiber from "fibers";
 import Future = require("fibers/future");