Replace self.pl.exception with self.exception
Replace self.pl.exception with self.exception

New function is checking for self.pl being set before using logger and also
removes the need of specifying explicit prefix="powerline".

Conflicts:
	powerline/__init__.py

dragon788/powerline,DoctorJellyface/powerline,prvnkumar/powerline,dragon788/powerline,junix/powerline,seanfisk/powerline,areteix/powerline,magus424/powerline,QuLogic/powerline,xfumihiro/powerline,firebitsbr/powerline,wfscheper/powerline,blindFS/powerline,keelerm84/powerline,darac/powerline,areteix/powerline,Liangjianghao/powerline,bartvm/powerline,kenrachynski/powerline,cyrixhero/powerline,S0lll0s/powerline,prvnkumar/powerline,DoctorJellyface/powerline,keelerm84/powerline,prvnkumar/powerline,darac/powerline,bezhermoso/powerline,firebitsbr/powerline,s0undt3ch/powerline,EricSB/powerline,QuLogic/powerline,EricSB/powerline,cyrixhero/powerline,IvanAli/powerline,kenrachynski/powerline,Liangjianghao/powerline,russellb/powerline,lukw00/powerline,areteix/powerline,xfumihiro/powerline,xfumihiro/powerline,IvanAli/powerline,blindFS/powerline,bartvm/powerline,seanfisk/powerline,Luffin/powerline,bartvm/powerline,darac/powerline,S0lll0s/powerline,S0lll0s/powerline,dragon788/powerline,russellb/powerline,kenrachynski/powerline,bezhermoso/powerline,s0undt3ch/powerline,wfscheper/powerline,xxxhycl2010/powerline,Luffin/powerline,IvanAli/powerline,junix/powerline,russellb/powerline,DoctorJellyface/powerline,xxxhycl2010/powerline,s0undt3ch/powerline,junix/powerline,cyrixhero/powerline,magus424/powerline,lukw00/powerline,magus424/powerline,xxxhycl2010/powerline,EricSB/powerline,blindFS/powerline,seanfisk/powerline,bezhermoso/powerline,Liangjianghao/powerline,Luffin/powerline,QuLogic/powerline,lukw00/powerline,firebitsbr/powerline,wfscheper/powerline