change 'Host' object's 'host' attribute to 'host_name'
change 'Host' object's 'host' attribute to 'host_name'

The function __repr__ of Host class which is located in hosts.py try to
access 'host' attribute, source code is "self.host",But in fact, Host object
don't has this attribute, it should be 'host_name'! We can find this attribute
from nova/api/openstack/compute/contrib/hosts.py file.

So I simply change 'self.host' to 'self.host_name'.

Change-Id: Ie76ba04da7592a596ab728fec981e9a1dbcc6a5f
Fixes: bug 1210043

Shihta/python-novaclient,guptaankita/python-novaclient,citrix-openstack-build/python-novaclient,CCI-MOC/python-novaclient,takeshineshiro/python-novaclient,citrix-openstack-build/python-novaclient,guptaankita/python-novaclient,Shihta/python-novaclient,takeshineshiro/python-novaclient,akash1808/python-novaclient,ntt-sic/python-novaclient,mat128/python-novaclient,mat128/python-novaclient,ntt-sic/python-novaclient,akash1808/python-novaclient,metacloud/python-novaclient,metacloud/python-novaclient,JioCloud/python-novaclient,JioCloud/python-novaclient,CCI-MOC/python-novaclient