Update PLUMgrid plugin information
Update PLUMgrid plugin information

README was quite oudated and created confusion
among users.

Updated the information after decomposition.

Change-Id: I78bf8dec20ba2ceb644d4565035d29bbf53cb3b5

jumpojoy/neutron,chitr/neutron,MaximNevrov/neutron,javaos74/neutron,wolverineav/neutron,eonpatapon/neutron,noironetworks/neutron,dhanunjaya/neutron,cloudbase/neutron,jumpojoy/neutron,asgard-lab/neutron,watonyweng/neutron,dims/neutron,wolverineav/neutron,JianyuWang/neutron,sebrandon1/neutron,JianyuWang/neutron,apporc/neutron,cloudbase/neutron,glove747/liberty-neutron,barnsnake351/neutron,mahak/neutron,vivekanand1101/neutron,mahak/neutron,adelina-t/neutron,suneeth51/neutron,dhanunjaya/neutron,yanheven/neutron,mandeepdhami/neutron,SamYaple/neutron,sasukeh/neutron,sasukeh/neutron,suneeth51/neutron,yanheven/neutron,mattt416/neutron,huntxu/neutron,mandeepdhami/neutron,klmitch/neutron,shahbazn/neutron,glove747/liberty-neutron,eayunstack/neutron,huntxu/neutron,adelina-t/neutron,silenci/neutron,igor-toga/local-snat,eonpatapon/neutron,shahbazn/neutron,MaximNevrov/neutron,mmnelemane/neutron,noironetworks/neutron,bigswitch/neutron,javaos74/neutron,jacknjzhou/neutron,silenci/neutron,neoareslinux/neutron,wenhuizhang/neutron,skyddv/neutron,sebrandon1/neutron,openstack/neutron,mmnelemane/neutron,skyddv/neutron,swdream/neutron,klmitch/neutron,swdream/neutron,wenhuizhang/neutron,igor-toga/local-snat,cisco-openstack/neutron,watonyweng/neutron,paninetworks/neutron,paninetworks/neutron,takeshineshiro/neutron,vivekanand1101/neutron,cisco-openstack/neutron,chitr/neutron,bigswitch/neutron,openstack/neutron,apporc/neutron,barnsnake351/neutron,mattt416/neutron,dims/neutron,asgard-lab/neutron,jacknjzhou/neutron,SamYaple/neutron,takeshineshiro/neutron,mahak/neutron,neoareslinux/neutron,openstack/neutron,eayunstack/neutron