New module [ufw]: this module handles Ubuntu UFW operations
* Updated documentation related to IPv6 usage.

BugFixes:
* Solved the default_policy and state mutual exclusive status.
* Fixed changed status for IPv6 addresses.
Added @otnateos patch.
Escaped UFW rule name.
Merge https://github.com/ansible/ansible/pull/5518
Merge https://github.com/ansible/ansible/pull/5518