Cleaning up inactive resources

SeBS keeps a list of cached cloud resources. However, the cache entries can become stale and invalid - this primarily applies to local deployment, where containers will be easily removed. Right now, a cached but removed container will throw an exception and force users to manually fix cache entries. We should be able to do it automatically.

• Detect old containers and reject them, issuing a warning.
• Add option to sebs resources to clean up local containers.
• Add option to sebs resources to look for and stop remove orphaned containers, e.g., Azure CLI after crash; a complete killswitch.