Pylint inspired cleanup (#1070115)

Related: rhbz#1070115

Signed-off-by: mulhern <amulhern@redhat.com>
Add a test file for DASD handling (#1070115)

Related: rhbz#1070115

Signed-off-by: mulhern <amulhern@redhat.com>
Condense and comment some devicelibs.dasd methods (#1070115)

Related: rhbz#1070115

Signed-off-by: mulhern <amulhern@redhat.com>