ListAttr: new attribute type for lists of literals
ListAttr: new attribute type for lists of literals

used in: interface->addresses, rule->in-ports, rule->out-ports

Signed-off-by: Guillermo Ontanon <d2262e90afe20c720e6771813c0217250cb2d4b2@midokura.jp>

midokura/python-midonetclient,midonet/python-midonetclient,midonet/python-midonetclient,midokura/python-midonetclient