Fix euca-get-password failure with no passwordData
Fix euca-get-password failure with no passwordData

Eucalyptus may omit passwordData elements from its responses completely
when instances don't have password data.  Boto isn't prepared for this,
so we catch it and fix it here instead.

Fixes TOOLS-73

nagyistoce/euca2ools,gholms/euca2ools,nagyistoce/euca2ools,vasiliykochergin/euca2ools,jhajek/euca2ools,gholms/euca2ools,jhajek/euca2ools,vasiliykochergin/euca2ools