git checkout's stderr v stdout usage

[prateekrungta]

```
  git checkout -b new_branch
```

Git does what's asked except that Git's success response ("Switched to a new branch 'new_branch'"), goes to to stderr instead of stdout.

This feels against standard unix conventions of what to output to stderr v stdout. It's an extra jump that people scripting `Git` keep running into when they encounter this behaviour. For e.g. other users have complained about this as far back as 2010: http://git.661346.n2.nabble.com/Bugreport-Git-responds-with-stderr-instead-of-stdout-td4959280.html

I'd like to suggest changing informational messages to stdout, and erroneous ones to stderr. May I submit a patch to change this behaviour?