Returns same as `get_dict_diff`, but as a readable string.

def get_dict_diff_str(d1, d2, title):
    """Returns same as `get_dict_diff`, but as a readable string.
    """
    added, removed, changed = get_dict_diff(d1, d2)
    lines = [title]

    if added:
        lines.append("Added attributes: %s"
                     % ['.'.join(x) for x in added])
    if removed:
        lines.append("Removed attributes: %s"
                     % ['.'.join(x) for x in removed])
    if changed:
        lines.append("Changed attributes: %s"
                     % ['.'.join(x) for x in changed])

    return '\n'.join(lines)