Add a file to the git repo

    This method does the same than a ::

        $ git add filename

    Keyword Arguments:
        :filename: (str) -- name of the file to commit

    Returns:
        <nothing>

def add_file_to_repo(filename):
    """Add a file to the git repo

    This method does the same than a ::

        $ git add filename

    Keyword Arguments:
        :filename: (str) -- name of the file to commit

    Returns:
        <nothing>
    """
    try:
        repo = Repo()
        index = repo.index
        index.add([_delta_dir() + filename])
    except Exception as e:
        print("exception while gitadding file: %s" % e.message)