Fixing issue #54

Whell that was easy...
Unifying logging verbosity

Both commands now share same verbosity behavior, and command line
parsing.
Fixed image pulling

It seems no one was calling prvode_image method, and even if they did
there was a python3 bug in it (filter returns a lazy sequence and always
evaluates to True).

Some other python3 compat. bug fixes, and renameing provide_image to
ensure_image.