Handle gitfiles when retrieving branch name
Handle gitfiles when retrieving branch name

Move code to parse a .git file from the do_status method to a new method
shared with get_branch_name so that branch name can be retreived from
repositories which use a .git file.

Closes #634.

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