ioworker: Don't do empty sends
ioworker: Don't do empty sends

We now only call send() if we actually have buffered data.
Stupidly, this matters.

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