Less file copying, more performance

Note: Fasten your seat belts! This PR speeds things up considerably.

* Custom express based development server
  * Serves from different directories and thus avoids unnecessary file copying. No more copying of the vendor directory!
  * less code
* `time-grunt` can show you the execution time of the various grunt tasks. Just install it via `npm install --save-dev time-grunt`
* Changed postinstall hook. Npm automatically searches locally for bower even if we omit the relative path. It's short and works on windows. :)