tools: Set default timezone using engine-config

Enable the vdc_options DefaultWindowsTimeZone and
DefaultGeneralTimeZone to be set using engine-config.

Change-Id: I8a9b0149d2d8065e1fc3a367eec72f8105806a64
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=974982
Signed-off-by: Martin Betak <mbetak@redhat.com>
Signed-off-by: Roy Golan <rgolan@redhat.com>