run.py: Remove global variable usage

Previously, the variables image_file, cmd_args and opt_path were used
globally along the run.py script, I did not consider this convenient and
thus, opted to convert these global variables, into one variable that is
passed as a parameter.

This variables was renamed to options, with the mindset that, if
desired, this variable could come from a configuration file, thus making
the passing of command line arguments optional. So, if this
functionality for a configuration file... Or perhaps default values, be
added to the script, there would not be much need for refactoring (or
renaming) as there would with these global variables.

Reviewed-by: Tomasz Grabiec <tgrabiec@gmail.com>
Signed-off-by: Juan Antonio Osorio Robles <jaosorior@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>