* Separate service for NetworkACL - "NetworkACL" service
* allow having just one network supporting LB in the VPC
* perform check against VPC when upgrade network to the new network offering (the same set of checks when you add new network to the VPC)
1) Added API frameworks for the feature. New commands:
* CreateVPCCmd
* ListVPCsCmd
* DeleteVPCCmd
* UpdateVPCCmd
* CreateVPCOfferingCmd
* UpdateVPCOfferingCmd
* DeleteVPCOfferingCmd
* ListVPCOfferingsCmd
2) New db tables:
* `cloud`.`vpc`
* `cloud`.`vpc_offerings`
* `cloud`.`vpc_offering_service_map`
and corresponding VO/Dao objects.
Added vpc_id field to `cloud.`networks` table - not null when network belongs to VPC
3) New Manager and Service interfaces- VpcManager/VpcService
4) Automatically create new VpcOffering (if doesn't exist) on system start
5) New Action events:
* VPC.CREATE
* VPC.UPDATE
* VPC.DELETE
* VPC.OFFERING.CREATE
* VPC.OFFERING.UPDATE
* VPC.OFFERING.DELETE