Support new IPv6 subnet modes in Neutron

This addresses addition of two new IPv6 subnet modes
called IPv6_RA_mode and IPv6_address_mode options in Neutron
at the time of creating an IPv6 subnet.

There are fixed values for both these modes.
They can be set to no_attribute_value or one of - slaac,
dhcpv6_stateful or dhcpv6_stateless.

These values represent how Router Advertisements (RAs) are
made for IPv6 address Neighbor discovery for VMs.

Co-Authored-By: Akihiro Motoki <motoki@da.jp.nec.com>
Implements: blueprint neutron-subnet-mode-support
Change-Id: I97abd3642b7da94cda85425534d934f30feb86d2
Merge "Support new IPv6 subnet modes in Neutron"
Fix password reveal icon for Bootstrap 3

Bootstrap 3 uses different classes for icons, so a change in the
CSS and JavaScript is needed to keep the password reveal button
working.

Change-Id: If963b8b0805a6a0506bf3ef625c4271bf4d91067
Merge branch 'master' of https://github.com/openstack/horizon