Add ip retention model
Add lease_time to lease_policies
Update LeasePolicy#allocate_ip to add expiration time to ip_lease
Add ip retention events
NodeApi::IpLease: Add support for ip retention
Add support for lease time
Refactor NodeApi::LeasePolicy
Replace pry debugger
Add Vnet::Openflow::Manager
Add IpRetentionManager
Supervise Service::Vnmgr
Add support for ip_retention grace time
Merge branch 'master' into feature-ip-retention

Conflicts:
	vnet/lib/vnet/endpoints/1.0/lease_policies.rb
Fix spec
Fix a pagination extension issue
Some refactorings
Use `raise` instead of `return`
Merge branch 'master' into feature-ip-retention
Add ItemVnetBase to autoload
Merge pull request #213 from axsh/feature-ip-retention

Feature ip retention