Add a simple test of generateBackupPassphrase() result format

Signed-off-by: mulhern <amulhern@redhat.com>
Use range instead of xrange in generateBackupPassphrase()

There is no real gain to using xrange in Python 2 and in Python 3 range is
a generator anyway.

Signed-off-by: mulhern <amulhern@redhat.com>
Disable redefined-builtin warning.

All redefinitions are python 2/3 compatibility redefinitions.

Signed-off-by: mulhern <amulhern@redhat.com>
Use add_metaclass instead of with_metaclass.

with_metaclass hides descent from object from pylint analyses and leads
to tons of messages arising from the analysis' belief that it is dealing
with old-style classes.

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