core: Move NetworkLabel entity to pseudo package

According to the suggeted in
http://gerrit.ovirt.org/#/c/22802/5/backend/manager/modules/common/src/main/java/org/ovirt/engine/core/common/businessentities/network/NetworkLabel.java
and since the NetworkLabel isn't a real business entity,
it is moved to a /businessentities/pseudo/ package.

Change-Id: I74b897dce328a2ee2869096ec9bc53e3a8ec5a9f
Signed-off-by: Moti Asayag <masayag@redhat.com>