Add minimalistic hello world HTTP service

Starts a HTTP server and registers an actor that implements a very basic
service which just returns 'Hello World'.

The code is mostly taken from the spray template github repo
(https://github.com/spray/spray-template/blob/on_spray-can_1.3/src/main/scala/com/example/MyService.scala).
I just updated versions and replaced spec2 with scalatest.
Add a Basic Auth protected path

In order to test the Togglz username activation strategy we need some
kind of authentication. This commit add a Basic Auth protected path
'/secured'.