Git Bash: Replace with a wrapper around msys.bat that hides the cmd window

See http://superuser.com/a/140077/136835.

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>
/etc/profile: Set the console window title separately from the prompt

This simplifies customizing the prompt.

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>