README: add VAGRANT_DEFAULT_PROVIDER

Signed-off-by: Hiroshi Miura <miurahr@linux.com>
kvm: add vnc console

Signed-off-by: Hiroshi Miura <miurahr@linux.com>
Merge pull request #27 from miurahr/support-vnc-console

kvm: add vnc console
Merge pull request #26 from miurahr/default-provider

README: add VAGRANT_DEFAULT_PROVIDER