task_create function is added to create a virtual network.
temporary hack: to see if to_hash is handled properly between vnmgr and the models in vdc
The model base class invokes a method of the database_mediator.
Added task_destroy in network.sh
Added after_create method through model hook.
Deleted after_create hook in base_new class
Added helper methods for ovs-vsctl/brctl
Added templates for openvz
Added vsctl_path to hva.conf
Modified nic_helper and hypervisor drivers.
The models do not send requests to the vdc_vnet_plugin when it is not available.
Modified the dcell connection configurable.
Fixed dcell initialization. (Specify adapter, host and port explicitly)
Fixed some mistakes, raising exception and indentation.
Merge pull request #331 from axsh/feature-vdc-vnet-integration

Feature vdc vnet integration