vm_definition: set secmodel attribute from xml

lib/vagrant-kmv/util/vm_definition.rb:
 + retrieve secmodel from domain xml in initialize.
 + fixed #226

Signed-off-by: Hiroshi Miura <miurahr@linux.com>
vm_definition: set secmodel when import

fixed #226

security model should be configured when importing.
when creating volume, only label is required.

Signed-off-by: Hiroshi Miura <miurahr@linux.com>