remove logic from app kernel

moves bundle loading into a new class and makes CoreBundle and BundleBundle use GravitonBundleInterface.
proper config loading

BundleBundle Bundles should load additional config during
DependencyInjections prepend phase. This makes the silly
config generation step obsolete. Next I need to finally grok
routing to do the same thing down there.
remove composer script

This was clearly not the way to do things around here.
I'm quite happy with the current solution as implemented
in CoreBundle and will only need to add routing later.
Merge branch 'feature/refactor-bundle' into develop

This concludes getting rid of the composer scripts...