fix(git-cmd): use LC_ALL instead of LC_MESSAGES
fix(git-cmd): use LC_ALL instead of LC_MESSAGES

Previously, only program messages where forced to the C-locale, now
we force the entire program. That way, we should assure a remote
will not provide us with branch information in any other language but
english.

Related to #290

bwrsandman/GitPython,avinassh/GitPython,gitpython-developers/gitpython,breavo/GitPython,manasdk/GitPython,dpursehouse/GitPython,zsjohny/GitPython,h4ck3rm1k3/GitPython,zsjohny/GitPython,gitpython-developers/GitPython,avinassh/GitPython,cdht/GitPython,breavo/GitPython,StyXman/GitPython,ghtdak/GitPython,StyXman/GitPython,nvie/GitPython,ghtdak/GitPython,expobrain/GitPython,dpursehouse/GitPython,gitpython-developers/gitpython,pengshp/GitPython,avinassh/GitPython,bwrsandman/GitPython,jeblair/GitPython,expobrain/GitPython,pengshp/GitPython,gitpython-developers/GitPython,StyXman/GitPython,roidelapluie/GitPython,cdht/GitPython,bwrsandman/GitPython,cdht/GitPython,nvie/GitPython,beni55/GitPython,jeblair/GitPython,pengshp/GitPython,manasdk/GitPython,beni55/GitPython,h4ck3rm1k3/GitPython,roidelapluie/GitPython,zsjohny/GitPython