* Fix: startup script was throwing FileNotFoundError

See
https://stackoverflow.com/questions/44557347/why-do-i-get-an-error-when-i-try-to-run-donkeycar-server-using-the-docker-image
for details

* Added datasets folder to start server script to fix bug where training fails without it

* add protocol to remote url if not specified in drive script

* added checks that remote_url was specified, with protocol and port