Add space after the dot in staged indicator

[aharonha]

[vpavic]

I'm aware this is quite old PR, but still - if you're using Ubuntu you probably don't need this change but rather an appropriate theme. See:

• https://github.com/magicmonty/bash-git-prompt#ubuntu-themes
• https://github.com/magicmonty/bash-git-prompt/blob/master/themes/Default_Ubuntu.bgptheme

[guenhter]

@aharonha thx for your contribution