Easy script that allows to migrate all commits to new email and username, just call it with your username and email as arguments and wait until everything is finished.

MigrateCommits.sh

#!/bin/sh

NAME=${1}
OLDEMAIL=${2}
EMAIL=${3}

curl --silent -X GET https://api.github.com/users/${NAME}/repos > repos.json
REPOS=$(cat ./repos.json | grep "\"html_url\": \"https://github.com/${NAME}/" | cut -d'"' -f4)

# Modified example https://help.github.com/articles/changing-author-info/

for i in ${REPOS[@]}; do
	echo "Overwriting $i"
	git clone --bare "$i"
	cd $(basename "$i")
	git filter-branch --env-filter '
	if [ "$GIT_COMMITTER_EMAIL" = "$OLDEMAIL" ]
	then
    		export GIT_COMMITTER_NAME="$NAME"
    		export GIT_COMMITTER_EMAIL="$EMAIL"
	fi
	if [ "$GIT_AUTHOR_EMAIL" = "$OLDEMAIL" ]
	then
    		export GIT_AUTHOR_NAME="$NAME"
    		export GIT_AUTHOR_EMAIL="$EMAIL"
	fi
	' --tag-name-filter cat -- --branches --tags
	git push --force --tags origin 'refs/heads/*'
	cd ..
done