Add a new script to rename the commit username of a git repo.

changeuser.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+git filter-branch --commit-filter '
+if [ "$GIT_COMMITTER_NAME" = "OLD_USERNAME" ];
+then
+  GIT_COMMITTER_NAME="NEW_USERNAME";
+  GIT_AUTHOR_NAME="NEW_USERNAME";
+  GIT_COMMITTER_EMAIL="EMAIL_NEW_USERNAME";
+  GIT_AUTHOR_EMAIL="EMAIL_NEW_USERNAME";
+  git commit-tree "$@";
+else
+  git commit-tree "$@";
+fi' HEAD