gui.topology: Remove source type and dest type Link attributes.
gui.topology: Remove source type and dest type Link attributes.

Also some refactoring

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