topology: getEntityByID() failure not fatal; Add missing import
topology: getEntityByID() failure not fatal; Add missing import

Previously, a call to getEntityByID() for an entity that didn't exist
was fatal.  Now it's not by default, but the behavior is optional.

Also, util.addresses wasn't being imported, but should have been.

PrincetonUniversity/pox,denovogroup/pox,diogommartins/pox,kpengboy/pox-exercise,PrincetonUniversity/pox,carlye566/IoT-POX,jacobq/csci5221-viro-project,andiwundsam/_of_normalize,kulawczukmarcin/mypox,chenyuntc/pox,waltznetworks/pox,MurphyMc/pox,VamsikrishnaNallabothu/pox,jacobq/csci5221-viro-project,xAKLx/pox,kavitshah8/SDNDeveloper,carlye566/IoT-POX,kulawczukmarcin/mypox,xAKLx/pox,noxrepo/pox,waltznetworks/pox,denovogroup/pox,MurphyMc/pox,chenyuntc/pox,diogommartins/pox,pthien92/sdn,xAKLx/pox,kpengboy/pox-exercise,waltznetworks/pox,kpengboy/pox-exercise,adusia/pox,diogommartins/pox,MurphyMc/pox,MurphyMc/pox,jacobq/csci5221-viro-project,kpengboy/pox-exercise,waltznetworks/pox,VamsikrishnaNallabothu/pox,kpengboy/pox-exercise,pthien92/sdn,xAKLx/pox,carlye566/IoT-POX,denovogroup/pox,kulawczukmarcin/mypox,noxrepo/pox,waltznetworks/pox,adusia/pox,jacobq/csci5221-viro-project,denovogroup/pox,adusia/pox,noxrepo/pox,andiwundsam/_of_normalize,MurphyMc/pox,xAKLx/pox,diogommartins/pox,chenyuntc/pox,jacobq/csci5221-viro-project,VamsikrishnaNallabothu/pox,PrincetonUniversity/pox,andiwundsam/_of_normalize,andiwundsam/_of_normalize,carlye566/IoT-POX,kulawczukmarcin/mypox,VamsikrishnaNallabothu/pox,PrincetonUniversity/pox,kavitshah8/SDNDeveloper,VamsikrishnaNallabothu/pox,adusia/pox,adusia/pox,kulawczukmarcin/mypox,pthien92/sdn,noxrepo/pox,chenyuntc/pox,chenyuntc/pox,PrincetonUniversity/pox,pthien92/sdn,kavitshah8/SDNDeveloper,carlye566/IoT-POX,pthien92/sdn,kavitshah8/SDNDeveloper,diogommartins/pox,denovogroup/pox