Add IPv6 Support for Rhel.
This patch does the following:

1. Adds support to process network config with IPv6
2. Adds support to display 'ifconfig -a' information for IPv6
3. Adds support to display routing information for IPv6
Added unittests for IPv6 support for RHEL
IPv6 support for rhel distro
  
- Saw an issue in my earlier commit with multiple NICs. This commit
  fixes that issue, along with the indentation issue
Updated unittests
 + Scenario with multiple NICs
IPv6 support for rhel distro

When the ubuntu networking info file has ipv6 addresses inside
it we need to make sure that we parse that information out and
place it (at least) in the rhel network configuration writing.

In later patches the other distros that use this parsed network
configuration will likely also need to be updated (ubuntu and
debian already should function as expected with regard to ipv6
support).