Add sign-off statement to component description

• • • • UNDER DISCUSSION **** The Sign-off statement consists of a line in the submission description file that contains a sign-off keyword, the name of the submitter, and the e-mail-address of the submitter.
        It is used to confirm that the submission is bound to the GENIVI Contributors' License Agreement (GCLA).
        Possible sign-off keywords and meanings are defined in the GCLA.
        No Sign-off statement may be added if no GCLA has been signed.

Sign-off process might be eventually part of the committing process on git