Add --global to all git configuration commands

Author: pcapriotti

git.go

@@ -83,10 +83,10 @@ func (g *GitClient) Init(branch string) error {
 	if err := g.command("git", "checkout", "-b", branch).Run(); err != nil {
 		return fmt.Errorf("checkout to '%s' failed: %s", branch, err)
 	}
-	if err := g.command("git", "config", "user.name", "concourse-ci").Run(); err != nil {
+	if err := g.command("git", "config", "--global", "user.name", "concourse-ci").Run(); err != nil {
 		return fmt.Errorf("failed to configure git user: %s", err)
 	}
-	if err := g.command("git", "config", "user.email", "concourse@local").Run(); err != nil {
+	if err := g.command("git", "config", "--global", "user.email", "concourse@local").Run(); err != nil {
 		return fmt.Errorf("failed to configure git email: %s", err)
 	}
 
@@ -108,7 +108,7 @@ func (g *GitClient) Init(branch string) error {
 		}
 	}
 
-	if err := g.command("git", "config", "url.https://.insteadOf", "git://").Run(); err != nil {
+	if err := g.command("git", "config", "--global", "url.https://.insteadOf", "git://").Run(); err != nil {
 		return fmt.Errorf("failed to configure github url: %s", err)
 	}
 	return nil