Documented dependency injected routers

* Fixed a bug in routes dependency ordering
* Explained clearly the migration approach in the 2.4 migration guide
* Updated as many code samples as I could find to use dependency
  injected routers
* Documented how to use the injected router in a compile time injected
  application
* Updated all Activator templates to use dependency injected router
Merge pull request #3428 from jroper/routes-injected-documentation

Documented dependency injected routers