Integrated generic install-node-modules for React Native

Summary:
Wacky nodeModules.js is replaced with install-node-modules.js.
A few concerns to address:
- I did not make it a `hg mv nodeModules.js ..../install-node-modules.js` because I want to start with clean-ish slate and have a good peer review to the script
- I did not want to use external dependencies for install-node-modules.js because I want this script to startup as fast as possible and don't want to either check in its dependencies or use yarn to install them. Otherwise I would use shell.js, node-fetch and optimist, still an option if this script proves to be a hassle to support

Things to come:
- hook up jsbuddy and flow on install-node-modules.js
- yarnpkg/yarn#576
- yarnpkg/yarn#569
- yarnpkg/yarn#570

Usage for fbsource projects:
```
fbcode/react_native/kpm/wrapper/install-node-modules.sh fbsource/.../js-project
```

Reviewed By: yungsters

Differential Revision: D3996416

fbshipit-source-id: 078b2ca5c076c2c6e2e7209945e59aaa31ebc4aa

fb-examples/bin/shipit_react-native.php-example

@@ -36,7 +36,7 @@ final class ShipItReactNative extends FBShipItCLI {
           ImmVector {
             '@(^|/)node_modules/@',
             '@(^|/)npm-shrinkwrap.json@',
-            '@(^|/)fbkpm.lock@',
+            '@(^|/)yarn.lock@',
             '@(^|/)packager/react-packager/src/packager_experimental/@',
           },
         )