Feature/setup protractor for testing

@bajtos 

Fixes #396
For posterity, here is the issue tracking the cleanup task: https://github.com/strongloop/loopback/issues/700

The sandbox directory is created and used by `test-server.js`. Since this patch is moving the test-server one level up in the directory tree, so is the `sandbox` dir moving up one level.

I don't mind cleaning this up after the PR is landed.