Improving test environment with expect.js, karma and Sauce Labs

Using:
 - expect.js (instead of chai) as it is also compatible with
   old versions of IE
 - karma which is the new version of testacular
 - Sauce Labs to automatically test noder on several browsers
Loader plugins
Allowing the resolver and loader to be configured at run time.
Improving configuration of built-in modules.
Improving build time by avoiding rebuilds of the bootstrap package.
Allowing the error context configuration to be customized.