Remove blueprint from pcep-ietf-stateful

This container seems to be a bunch of stateless activators. The other part is a few booleans which can be neatly tucked away behind OSGi Config Admin.

Refactor and use OSGi DS instead of blueprint.

The PCEPStatefulCapability bit needs to be refactored so that users can pass in the configuration – it is currently not used in OSGi env, so there is no loss of functionality w.r.t. current status.