Improve task results cli cmd
Improve task results cli cmd

Support new argument

--pretty:
  If none or json => print resuls as json.dumps()
  If pprint - use pprint to display results

Change-Id: I6f54952cbbe24ebf3fa3d430025b947ff7a99cb6

vganapath/rally,openstack/rally,go-bears/rally,ytsarev/rally,amit0701/rally,pyKun/rally,gluke77/rally,pandeyop/rally,redhat-openstack/rally,openstack/rally,eayunstack/rally,varunarya10/rally,amit0701/rally,vponomaryov/rally,aforalee/RRally,yeming233/rally,vganapath/rally,amit0701/rally,paboldin/rally,pyKun/rally,go-bears/rally,openstack/rally,group-policy/rally,afaheem88/rally,vganapath/rally,vefimova/rally,eayunstack/rally,vefimova/rally,eonpatapon/rally,vponomaryov/rally,shdowofdeath/rally,redhat-openstack/rally,paboldin/rally,ytsarev/rally,cernops/rally,openstack/rally,vganapath/rally,gluke77/rally,aplanas/rally,varunarya10/rally,gluke77/rally,yeming233/rally,group-policy/rally,paboldin/rally,pandeyop/rally,group-policy/rally,aplanas/rally,cernops/rally,gluke77/rally,afaheem88/rally,eayunstack/rally,shdowofdeath/rally,eonpatapon/rally,aforalee/RRally