Support IPv6
Merged and fiexed conflicts with r515
Fixed conflict with r515
Fixed for pep8
Fixed bug
Fixed bug in libvirt
Some Bug Fix
The _update method in base Instance class overides dns_name_v6,so fixed it.
Fixed bug in nova_project_filter_v6
Fixed misspelled variable
Removed debug message which is not needed.
Fixed:Create instance fails when use_ipv6=False
Fixed for pep8
missing _()
changed exception class
Fixed for pep8
Remove temporary debugging
Add DescribeInstanceV6 for backward compatibility
Fixed bug
Merged with r548
Change command to get link local address
Remove superfluous code