command.py: Cleaned up pylint/pep8 violations

I noticed when running pylint (as the SUBMITTING_PATCHES file directs)
that there were a few violations reported. This makes it difficult
to see violations I might have introduced. This commit corrects all
pylint violations in the command.py script.

This script now has a pylint score of 10.0.

Change-Id: Ibb35fa9af0e0b9b40e02ae043682b3af23286748