libopenflow: Allow setting in_port in flip()
libopenflow: Allow setting in_port in flip()

It's often the case that you want to unset the inport or set it to
something different.  This makes it easier to do so.  It's possible that
we should unset it by default (default value = None).

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