Replace unicode() with u() in theme.py
Replace unicode() with u() in theme.py

Fixes #271

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