cephadm: fixes to address PR requirements

cephadm: fixes to address PR requirements

Minor changes to address issues raised in the PR;
- formatting of ipv6 addresses
- missing docstrings
- NIC mtu and speed now int instead of string
- added NIC driver name
- removed discrete JSON method making gather-facts JSON only
- added upper/lower device lists to show NIC relationships
- added hostname to the JSON!
- added selinux/apparmor status
- added timestamp (epoch) for the gather-facts run
- added system uptime (secs)

Closes:

Signed-off-by: Paul Cuzner <pcuzner@redhat.com>