Some minor kvm refactoring wrt hotplug
Some minor kvm refactoring wrt hotplug

Make _CallHotplugCommands() a classmethod, rename _PassTapFd()
to _HMPPassFd() and make it a wrapper for MonitorSocket's GetFd().

Signed-off-by: Dimitris Aragiorgis <4514117c4a99256e19437c7e3407c4ecbf98aec0@grnet.gr>
Reviewed-by: Helga Velroyen <2d0126b1ec6f9ec5cbec4a7012aa14faeaef10f5@google.com>

mbakke/ganeti,ganeti/ganeti,leshchevds/ganeti,dimara/ganeti,yiannist/ganeti,onponomarev/ganeti,ganeti/ganeti,ganeti-github-testing/ganeti-test-1,bitemyapp/ganeti,apyrgio/ganeti,leshchevds/ganeti,dimara/ganeti,ganeti/ganeti,leshchevds/ganeti,ganeti-github-testing/ganeti-test-1,apyrgio/ganeti,yiannist/ganeti,mbakke/ganeti,yiannist/ganeti,andir/ganeti,grnet/snf-ganeti,bitemyapp/ganeti,mbakke/ganeti,andir/ganeti,onponomarev/ganeti,andir/ganeti,grnet/snf-ganeti