core: set nic name on import template

Fix a regression that was caused by a recently-introduced refactoring to
OvfReader: the name for NICs wasn't set in the import template
operation, thus caused the import template operation to fail when the
template which was about to be imported contained NIC.

Change-Id: I19352e715921794840cf4a39d59cdfad4f9221f4
Bug-Url: https://bugzilla.redhat.com/1136895
Signed-off-by: Arik Hadas <ahadas@redhat.com>