packaging: introduce the ovirt-engine-lib package

a python library, and in future can be more, to be used by any
component, not locked by versionlock so it can be used by all but must
be backward compatible.

Change-Id: I4847f4fdbac5eb46d2a8f8780b9e515ff8a27982
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>