Files or directories can be specified on command line

Also adds argparse for argument passing, and the ability to skip waiting for the import to finish on the server side. Also includes omero.cli.cli_login to manage the login session, though this will always close your session after use which can be annoying if you created it outside of the script.

Import into dataset 7751:

./import.py --dataset 7751 z-series-on-trello.urlpattern

Import without waiting (--dataset will be ignored):

./import.py z-series-on-trello.urlpattern --wait 0