"repositories": [
        {
            "type": "vcs",
            "url": "https://github.com/clytemnestra/JMSTranslationBundle"
        }
    ],
   "require": {
         ....
        "jms/translation-bundle": "dev-keepmessages",
         ....
    },

Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

git remote add origin https://github.com/clytemnestra/JMSTranslationBundle