Refine the container SPIs to decouple them from a single JVM

The Deployable Container SPI is currently implemented across all containers assuming that events like start() and stop() are invoked from the same JVM.

Based on discussion held in this pull request, we'd like to refine this SPI to allow for the start(), stop() and possibly other events to be invoked from different JVMs. Note that this may also require rewrite of container adapters so that they're stateless by nature.