Reintroduce pyflakes optional dependency.
Reintroduce pyflakes optional dependency.

hackday-profilers/flocker,beni55/flocker,adamtheturtle/flocker,w4ngyi/flocker,achanda/flocker,agonzalezro/flocker,lukemarsden/flocker,lukemarsden/flocker,wallnerryan/flocker-profiles,AndyHuu/flocker,moypray/flocker,beni55/flocker,LaynePeng/flocker,wallnerryan/flocker-profiles,beni55/flocker,jml/flocker,mbrukman/flocker,adamtheturtle/flocker,mbrukman/flocker,adamtheturtle/flocker,LaynePeng/flocker,LaynePeng/flocker,Azulinho/flocker,wallnerryan/flocker-profiles,lukemarsden/flocker,hackday-profilers/flocker,runcom/flocker,Azulinho/flocker,moypray/flocker,1d4Nf6/flocker,mbrukman/flocker,AndyHuu/flocker,jml/flocker,Azulinho/flocker,AndyHuu/flocker,w4ngyi/flocker,moypray/flocker,agonzalezro/flocker,jml/flocker,w4ngyi/flocker,runcom/flocker,1d4Nf6/flocker,hackday-profilers/flocker,agonzalezro/flocker,achanda/flocker,1d4Nf6/flocker,runcom/flocker,achanda/flocker