Call setuid/setgid in script/git-proxy
Call setuid/setgid in script/git-proxy

In able to use the git proxy from Upstart (in Upstart versions which
don't support setgid/setuid themselves) without needing an extra
shell (su -c or equivalent) we might as well do this ourselves.

If all these conditions are met:
- RAILS_ENV=production
- We're running as root
- gitorious.yml specifies gitorious_user

we will switch the script to the gid and uid of the specified user.

deld/gitorious,spencerwp/mainline,ericbutters/eric-gitorious,gitorious/mainline,tigefa4u/gitorious-mainline,tigefa4u/gitorious-mainline,SamuelMoraesF/Gitorious,gitorious/mainline,elcom/gitorious,SamuelMoraesF/Gitorious,elcom/gitorious,elcom/gitorious,rae/gitorious-mainline,ericbutters/eric-gitorious,rae/gitorious-mainline,tigefa4u/gitorious-mainline,Gitorious-backup/mainline,tigefa4u/gitorious-mainline,gitorious/mainline,spencerwp/mainline,Gitorious-backup/mainline,deld/gitorious,deld/gitorious,elcom/gitorious,rae/gitorious-mainline,SamuelMoraesF/Gitorious,Gitorious-backup/mainline,Gitorious-backup/mainline,gitorious/mainline,spencerwp/mainline,ericbutters/eric-gitorious,SamuelMoraesF/Gitorious,spencerwp/mainline,rae/gitorious-mainline