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
1) Introduce new managers - ProjectManager and DomainManager. Moved all domain related code from AccountManager to DomainManager.
2) Moved some code from ManagementServerImpl to the correct managers.
3) New resource limit for Domain - Project