call vendor.py on remoto so it vendors itself

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
allow to call something when vendor requirements say so

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
adapt remoto imports for new optional vendoring

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>