Git Bash: Swap the order of arguments taken

This way it is more natural to specify MSYSTEM without specifying a start
directory.

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>
installer: Use "Git Bash.vbs" to start the environment to get a title icon

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