packaging: Use engine.conf for local configuration

This change moves the content of the /etc/sysconfig/ovirt-engine file to
the /etc/ovirt-engine/engine.conf file. The reason for this is that this
file is not only used by the service, but also by other tools, and in
other Linux distributions the sysconfig directory is not common.

Change-Id: I9b48f1fd78ebd891e93949f19fafefcffd377254
Signed-off-by: Juan Hernandez <juan.hernandez@redhat.com>