Feature vdc vnet integration

Reopened the branch since an error has been found in the integration test.

http://ci.wakame.jp/job/kvm.t12-integration-rw/1315/console

    22:48:18 [2014-03-16T22時48分18秒 #27294] time:1 eval:document_pair? load_balancer lb-oo8e7aso state terminated
    22:48:21 [2014-03-16T22時48分21秒 #27294] time:2 eval:document_pair? load_balancer lb-oo8e7aso state terminated
    22:48:24 [2014-03-16T22時48分24秒 #27294] time:3 eval:document_pair? load_balancer lb-oo8e7aso state terminated
    ...
    22:49:59 Ran 1 test.
    22:49:59 
    22:49:59 FAILED (failures=1)
    22:49:59 make: *** [test] エラー 1
    22:49:59 Build step 'Execute managed script' marked build as failure
    22:50:00 Notifying upstream projects of job completion
    22:50:00 Finished: FAILURE

This is due to missing some operation in the kvm driver.

http://ci.wakame.jp/job/kvm.pick-log/1172/console

    22:50:09 2014-03-16 22:48:55 JobContext thr=JobWorker[0/1] [ERROR]: Caught NameError: undefined local variable or method `bridge' for #<Dcmgr::Drivers::Kvm:0x007fc5771ed9f0>
    22:50:09 	/opt/axsh/wakame-vdc/dcmgr/lib/dcmgr/drivers/kvm.rb:168:in `block in poweron_instance'
    22:50:09 	/opt/axsh/wakame-vdc/dcmgr/lib/dcmgr/drivers/kvm.rb:165:in `each'
    22:50:09 	/opt/axsh/wakame-vdc/dcmgr/lib/dcmgr/drivers/kvm.rb:165:in `poweron_instance'