Used namedtuple for ReservationInfo
Used namedtuple for ReservationInfo

The code already uses a namedtuple for ResourceUsageInfo
and it is a nonsense to not use it for ReservationInfo.

Related-Blueprint: bp/better-quotas

Change-Id: I99666ac865fbdeef2d84353eff49d60b6d87fddc

takeshineshiro/neutron,chitr/neutron,mattt416/neutron,dims/neutron,shahbazn/neutron,igor-toga/local-snat,jumpojoy/neutron,skyddv/neutron,sebrandon1/neutron,silenci/neutron,MaximNevrov/neutron,neoareslinux/neutron,javaos74/neutron,asgard-lab/neutron,swdream/neutron,klmitch/neutron,dhanunjaya/neutron,glove747/liberty-neutron,asgard-lab/neutron,noironetworks/neutron,skyddv/neutron,adelina-t/neutron,barnsnake351/neutron,silenci/neutron,MaximNevrov/neutron,huntxu/neutron,JianyuWang/neutron,JianyuWang/neutron,mahak/neutron,mmnelemane/neutron,mattt416/neutron,openstack/neutron,SamYaple/neutron,eayunstack/neutron,jumpojoy/neutron,wolverineav/neutron,neoareslinux/neutron,dims/neutron,eayunstack/neutron,klmitch/neutron,glove747/liberty-neutron,SamYaple/neutron,dhanunjaya/neutron,openstack/neutron,openstack/neutron,cloudbase/neutron,mahak/neutron,sasukeh/neutron,takeshineshiro/neutron,huntxu/neutron,mahak/neutron,yanheven/neutron,noironetworks/neutron,sebrandon1/neutron,barnsnake351/neutron,sasukeh/neutron,igor-toga/local-snat,vivekanand1101/neutron,apporc/neutron,swdream/neutron,yanheven/neutron,apporc/neutron,wolverineav/neutron,chitr/neutron,bigswitch/neutron,shahbazn/neutron,bigswitch/neutron,vivekanand1101/neutron,adelina-t/neutron,cloudbase/neutron,mmnelemane/neutron,javaos74/neutron