Add a table and skeltons for ip retention container
Merge branch 'master' into feature-ip-retention-container

Conflicts:
	vnet/db/migrations/0001_origin.rb
Added active_interfaces table to database.
Update events and node api
Refactor ip_retention_container.rb
Add Vnet::NodeApi::IpLease.expire
Merge branch 'master' into feature-ip-retention-container
Replace IpRetentionManager with IpRetentionContanerManager
Renamed active * event helpers.
Added ActiveInterfaceManager.
Added event definitions for ActiveInterfaceManager.
Added an internal method for wait_for_loaded and use a public method wrapper.
Update IpRetentionContainerManager and implement its spec
Set lease_time_expired_at on before_create
Add spec for NodeApi::IpRetentionContainer
Implement endpoint for ip_retention_container
Add GET '/lease_policies/:uuid/ip_leases'
Add Vnet.logger
Replace Vnet::NodeApi.logger with Vnet.logger
Fix a manager name