status: lose dependence on StringIO
status: lose dependence on StringIO

buflist was being used, which isn't available in Python 3.

`Execute` was using StringIO to capture the output of `PrintWorkTreeStatus`,
only to redirect it straight to stdout.
Instead, just let `PrintWorkTreeStatus` do it's own thing directly to stdout.

for handling `_FindOrphans`, we swap StringIO for a list. Nothing was done
that needed a a file like object.

Change-Id: Ibdaae137904de66a5ffb590d84203ef0fe782d8b

ediTLJ/git-repo,qupai/git-repo,simbasailor/git-repo,couchbasedeps/git-repo,4455jkjh/repo,lipro-yocto/git-repo,aosp-mirror/tools_repo,FlymeOS/repo,derron/git-repo,mixedpuppy/git-repo,mozilla/git-repo,codetutil/git-repo,frogbywyplay/git-repo,FuangCao/git-repo,jingyu/git-repo,qioixiy/git-repo,ChronoMonochrome/repo,nuclearmistake/repo,FuangCao/git-repo,frogbywyplay/git-repo,biaolv/git-repo,testbetta/git-repo-pub,llg84/google_repo,chzhong/git-repo,GerritCodeReview/git-repo,mozilla/git-repo,slfyusufu/repo,lewixliu/git-repo,GerritCodeReview/git-repo,mixedpuppy/git-repo,flingone/git-repo,TheQtCompany/git-repo,zemug/repo,4455jkjh/repo,iAlios/git-repo,kangear/git-repo,llg84/google_repo,ediTLJ/git-repo,11NJ/git-repo,wavecomp/git-repo,FuangCao/repo,biaolv/git-repo,petemoore/git-repo,aosp-mirror/tools_repo,codetutil/git-repo,11NJ/git-repo,chzhong/git-repo,GatorQue/git-repo-flow,testbetta/repo-pub,darrengarvey/git-repo,zemug/repo,CyanogenMod/tools_repo,petemoore/git-repo,mer-tools/git-repo,couchbasedeps/git-repo,ronan22/repo,jingyu/git-repo,lipro-yocto/git-repo,kdavis-mozilla/repo-repo,mer-tools/git-repo,iAlios/git-repo,qioixiy/git-repo,chenzilin/git-repo,gbraad/git-repo,gbraad/git-repo,flingone/git-repo,simbasailor/git-repo,nuclearmistake/repo,kangear/git-repo,chenzilin/git-repo,lewixliu/git-repo,CyanogenMod/tools_repo,xyyangkun/git-repo,ChronoMonochrome/repo,derron/git-repo,dodocat/git-repo,testbetta/repo-pub,kdavis-mozilla/repo-repo,dodocat/git-repo,slfyusufu/repo,FlymeOS/repo,qupai/git-repo,GatorQue/git-repo-flow,wavecomp/git-repo,TheQtCompany/git-repo,ronan22/repo,xyyangkun/git-repo,gabbayo/git-repo,gabbayo/git-repo,FuangCao/repo,testbetta/git-repo-pub,darrengarvey/git-repo